Replacing HEPA Filters in AC Systems

Replacing HEPA Filters in AC Systems

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Common Issues with HEPA Filters in AC Systems



When discussing the topic of replacing HEPA filters in AC systems, it's important to address some common issues associated with these filters. A sudden rise in your energy bills could mean it’s time for HVAC Repair HVAC installation to optimize your heat exchanger performance. High-Efficiency Particulate Air (HEPA) filters are renowned for their ability to trap airborne particles, providing cleaner air and enhancing indoor air quality. However, despite their effectiveness, they can present certain challenges that need consideration.

One prevalent issue is the reduction in airflow. HEPA filters are designed to capture very fine particles, which means they have a denser structure compared to regular filters. This density can lead to increased resistance against airflow within an AC system. As a result, if not appropriately managed or if the system isn't designed to accommodate such a filter, it may cause strain on the HVAC unit's motor or reduce its efficiency over time. This underscores the importance of ensuring that the AC system is compatible with HEPA filters before installation.

Another challenge is the frequency of replacement. Due to their high filtration capacity, HEPA filters can become clogged more quickly than standard filters-especially in environments with high levels of dust, pollen, or other particulates. A clogged filter not only reduces air quality but also forces the HVAC system to work harder, potentially leading to higher energy consumption and increased wear and tear on the system components. Hence, regular monitoring and timely replacement of HEPA filters are crucial.

Cost is another factor worth noting when considering HEPA filter replacements. These filters tend to be more expensive than conventional ones due to their advanced design and superior material quality. While investing in HEPA filters can significantly improve air quality and benefit those with respiratory concerns or allergies, it's essential for consumers to weigh this cost against their specific needs and budget constraints.

Lastly, compatibility issues might arise when retrofitting older AC systems with new HEPA technology. Some older systems may not support these modern filters without necessary modifications or upgrades-a factor that could entail additional expenses for homeowners or businesses seeking improved filtration capabilities.

In conclusion, while HEPA filters offer substantial benefits by improving indoor air quality through superior particle removal capabilities, they also present certain challenges such as reduced airflow efficiency, frequent need for replacements, higher costs upfront compared to standard options, and potential compatibility concerns with existing HVAC systems. Being informed about these common issues allows users to make educated decisions about incorporating HEPA filtration into their AC systems effectively while maintaining optimal performance levels without unnecessary setbacks.

Signs Indicating the Need for Replacing HEPA Filters



High-Efficiency Particulate Air (HEPA) filters are a crucial component in air conditioning systems, particularly for those who prioritize clean and healthy indoor air. However, like any other part of an HVAC system, HEPA filters have a lifespan and eventually require replacement to maintain optimal performance. Identifying the signs indicating the need for replacing these filters is essential in ensuring that the AC system continues to function efficiently and effectively.

One of the primary indicators that a HEPA filter needs replacement is a noticeable decrease in airflow through the system. When the filter becomes clogged with dust, pollen, pet dander, and other particulates, it restricts airflow, making it harder for the AC unit to circulate air throughout the space. This can lead to uneven cooling or heating, causing discomfort and reducing the overall efficiency of the system. If you find yourself adjusting your thermostat more frequently or if certain areas within your home are not reaching desired temperatures as quickly as they used to, it may be time to check on your HEPA filter.

Another sign that suggests it's time for a replacement is an increase in energy bills without any apparent reason. As clogged filters force HVAC systems to work harder to pull air through obstructed ducts, they consume more energy than usual. This inefficiency not only raises utility costs but also exerts additional strain on the system's components, potentially leading to breakdowns or diminished lifespan.

A third indication involves increased dust accumulation around vents and within living spaces. If you notice more dust settling on surfaces despite regular cleaning routines, this might be due to an overworked HEPA filter failing at its job of trapping particles before they enter your home environment. Similarly, worsening allergy symptoms among inhabitants can point towards compromised indoor air quality resulting from ineffective filtration.

Additionally, unpleasant odors emanating from vents could signal that organic matter trapped inside a saturated HEPA filter has started decomposing due to moisture buildup-an issue especially prevalent in humid climates or during rainy seasons. Such smells not only compromise comfort but can also impact health if left unaddressed.

Lastly yet importantly; most manufacturers recommend routine inspection schedules specifying when replacements should occur based upon usage levels & environmental conditions surrounding installation sites themselves – following these guidelines ensures consistent protection against airborne contaminants while preserving equipment integrity over long-term operations where applicable too!

In conclusion: recognizing early warning signs associated with aging/inadequate functioning HEPAs enables proactive measures taken promptly thereby avoiding costly repairs later down line plus safeguarding family members' wellbeing alike! Regular maintenance checks alongside timely replacements represent wise investments guaranteeing cleaner healthier homes year-round regardless weather outside happens doing whatever does next…

Step-by-Step Guide to Replacing HEPA Filters

Step-by-Step Guide to Replacing HEPA Filters



Replacing HEPA filters in air conditioning (AC) systems is a crucial maintenance task that ensures optimal performance and air quality. These filters are designed to capture microscopic particles, including dust, pollen, mold spores, and other allergens, thus improving indoor air quality significantly. Over time, however, HEPA filters can become clogged with these particulates and lose their efficiency. This step-by-step guide will help you replace your AC system's HEPA filter effectively.

The first step in replacing the HEPA filter is identifying its location within your AC system. Typically, the filter is housed near the return duct or blower compartment of the unit. Refer to your AC system's manual for specific details about your model's configuration if you're unsure. Once located, turn off the power to the unit as a safety precaution before proceeding.

Next, carefully remove the access panel where the filter is housed. Depending on your model, this may require unscrewing bolts or simply unlatching clips. When opening this panel, take care not to damage any nearby components or wiring.

With access granted to the old filter, gently slide it out of its slot while being cautious not to agitate accumulated dust and debris into the surrounding area. It might be helpful to have a garbage bag handy so you can immediately dispose of it without spreading pollutants throughout your home.

Before installing a new filter, take a moment to clean around the empty slot using a damp cloth or vacuum with an appropriate attachment; this removes any residual dust that could impact airflow once the fresh filter is installed.

When choosing a replacement HEPA filter for your AC system, ensure it matches specifications recommended by your manufacturer-particularly in terms of size and filtration capability-to maintain efficiency and effectiveness.

Insert the new filter into its designated slot with attention paid towards directional arrows printed on its frame indicating proper airflow orientation relative to your AC setup. Securely close up any panels previously removed during disassembly ensuring all screws or latches are tightly fastened back into place.

Finally-and perhaps most importantly-restore power back onto your unit after confirming everything has been reassembled correctly! Monitor how well airflow feels now compared against prior experiences noting improved circulation alongside cleaner smelling output from vents which should indicate successful installation efforts overall!

In conclusion: regular replacement cycles every six months (or sooner if conditions dictate) foster healthier environments indoors through sustained operational efficacy across seasons whilst also extending service life expectancy generally associated with heating/cooling mechanisms themselves thereby representing wise investments both financially speaking long-term too!

Step-by-Step Guide to Replacing HEPA Filters

Benefits of Regularly Replacing HEPA Filters

Benefits of Regularly Replacing HEPA Filters



Regularly replacing HEPA filters in air conditioning (AC) systems is a crucial maintenance task that offers numerous benefits, enhancing both the performance of the system and the indoor environment's quality. High-Efficiency Particulate Air (HEPA) filters are renowned for their ability to trap tiny particles, including dust, pollen, mold spores, and even some bacteria and viruses. However, to maintain their efficiency and ensure optimal functioning of the AC system, these filters need to be replaced regularly.

One of the primary benefits of replacing HEPA filters is improved air quality. Over time, as HEPA filters become clogged with particles they have captured from the air, their ability to remove additional contaminants diminishes. This can lead to poorer air quality within your home or office space as small particles may bypass clogged filters. By changing these filters regularly, you help ensure that your AC system continues to circulate clean air, reducing allergens and potential irritants for those with respiratory issues or allergies.

Another significant advantage is enhanced energy efficiency. A clean filter allows for better airflow through the AC system. When a filter becomes clogged with dirt and debris, it forces the system's fan motor to work harder to push air through it. This increased workload requires more energy consumption which can drive up utility bills over time. Regular replacement of HEPA filters helps maintain efficient airflow, allowing your AC unit to operate at its optimal capacity without unnecessary energy expenditure.


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In addition to improving air quality and energy efficiency, routinely changing HEPA filters also prolongs the lifespan of your AC system. Clogged or dirty filters can cause undue stress on various components of an HVAC (heating, ventilation, and air conditioning) system by forcing it to work harder than necessary. Over time this added strain can lead to mechanical failures or reduce overall durability of key parts such as fans or compressors. Keeping fresh HEPA filters installed minimizes such risks by ensuring smooth operation.

Moreover, regular maintenance practices like replacing HEPA filters contribute significantly towards cost savings in terms of reduced repair expenses down the line due mainly because well-maintained systems encounter fewer breakdowns compared poorly maintained ones do experience quite often requiring costly repairs eventually if not addressed timely manner initially itself thus proving beneficial economically wise too!

Finally yet importantly too just alone especially given current times where health consciousness increasingly prevalent amongst people everywhere around world post-pandemic era importance maintaining healthy living spaces cannot overstated enough hence why regular replacements hold paramount importance safeguarding wellbeing occupants premises concerned always remain top priority list considerations any household commercial establishment alike nowadays undeniably so indeed fact matter!

Potential Risks of Neglecting HEPA Filter Replacement

Potential Risks of Neglecting HEPA Filter Replacement



Ensuring optimal indoor air quality is a priority for maintaining a healthy and comfortable living environment, and one crucial component in this endeavor is the regular replacement of HEPA filters in air conditioning (AC) systems. High-Efficiency Particulate Air (HEPA) filters are designed to capture at least 99.97% of particles as small as 0.3 microns, including dust, pollen, mold spores, and other airborne contaminants. However, neglecting the timely replacement of these filters can introduce several potential risks that affect both health and system efficiency.

One notable risk associated with failing to replace HEPA filters is compromised air quality. Over time, as these filters trap more particulates from the air, they become clogged and less effective at capturing new contaminants.

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This means that pollutants such as allergens and pathogens can circulate freely within the indoor environment, potentially exacerbating respiratory conditions like asthma or allergies among occupants.

Moreover, an overburdened filter puts undue stress on an AC system's fan motor due to restricted airflow. This inefficiency not only drives up energy consumption-leading to higher utility bills-but also increases wear and tear on the equipment itself. In extreme cases, it could result in costly repairs or even premature system failure.

Additionally, a neglected HEPA filter may contribute to moisture build-up within the AC unit because of diminished airflow. This accumulation provides an ideal breeding ground for mold and bacteria which can further degrade indoor air quality while posing serious health risks to inhabitants.

Finally, there are environmental considerations; obstructed filters cause systems to work harder than necessary which results in increased carbon emissions contributing negatively towards climate change efforts.

In conclusion, regularly replacing HEPA filters in AC systems is essential not just for maintaining good air quality but also for ensuring efficient operation of HVAC units while safeguarding occupant health against potential hazards posed by neglectful practices. By adhering strictly to recommended maintenance schedules provided by manufacturers or consulting with HVAC professionals when unsure about specific needs based on usage patterns ensures long-term benefits both economically and environmentally speaking.

Potential Risks of Neglecting HEPA Filter Replacement
Tips for Selecting the Right Replacement HEPA Filter for Your System
Tips for Selecting the Right Replacement HEPA Filter for Your System

Tips for Selecting the Right Replacement HEPA Filter for Your System



Selecting the right replacement HEPA filter for your AC system is crucial in maintaining optimal indoor air quality and ensuring the efficiency of your air conditioning unit. The process can seem daunting given the variety of options available, but understanding a few key factors will simplify your decision-making.

Firstly, it is essential to identify the specific requirements of your AC system. This involves checking the manufacturer's specifications detailed in the user manual or on their website. Each system has its own size and design constraints, which means not every HEPA filter on the market will be suitable for your unit. Using filters that do not meet these specifications could lead to reduced performance or even damage to your system.

Another critical consideration is the MERV (Minimum Efficiency Reporting Value) rating of the filter.

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MERV ratings range from 1 to 20, with higher numbers indicating greater filtration capability. For residential use, a MERV rating between 7 and 13 is generally adequate, effectively capturing common household allergens such as dust mites and pollen without overburdening most systems. However, if anyone in your home suffers from severe allergies or respiratory conditions, you might consider a higher-rated filter while ensuring compatibility with your AC model.

Durability and longevity are also important factors when choosing a replacement HEPA filter. Check how often each type of filter needs replacing; some may require frequent changes while others offer extended life spans. Filters that last longer can sometimes be more cost-effective despite a higher initial price because they reduce maintenance frequency.

Additionally, consider any additional features that may benefit your particular situation. Some filters come with antimicrobial treatments to prevent mold growth within the system-a useful feature if you live in a humid climate or have experienced mold issues before.

Finally, think about environmental impact and budgetary constraints. Many manufacturers offer eco-friendly products made from renewable materials or recyclable components at various price points, helping you make choices aligned with both environmental consciousness and financial considerations.

In conclusion, selecting the right replacement HEPA filter involves considering several factors: compatibility with your AC system's specifications, appropriate MERV ratings for effective filtration without compromising airflow, durability for cost-effectiveness over time, additional beneficial features like antimicrobial properties, and balancing ecological concerns with budget limits. By taking these elements into account thoughtfully during selection processes ensures improved air quality within homes while prolonging lifespan efficiencies associated across all installed HVAC units alike!

 

An air filter being cleaned

Indoor air quality (IAQ) is the air quality within buildings and structures. Poor indoor air quality due to indoor air pollution is known to affect the health, comfort, and well-being of building occupants. It has also been linked to sick building syndrome, respiratory issues, reduced productivity, and impaired learning in schools. Common pollutants of indoor air include: secondhand tobacco smoke, air pollutants from indoor combustion, radon, molds and other allergens, carbon monoxide, volatile organic compounds, legionella and other bacteria, asbestos fibers, carbon dioxide,[1] ozone and particulates.

Source control, filtration, and the use of ventilation to dilute contaminants are the primary methods for improving indoor air quality. Although ventilation is an integral component of maintaining good indoor air quality, it may not be satisfactory alone.[2] In scenarios where outdoor pollution would deteriorate indoor air quality, other treatment devices such as filtration may also be necessary.[3]

IAQ is evaluated through collection of air samples, monitoring human exposure to pollutants, analysis of building surfaces, and computer modeling of air flow inside buildings. IAQ is part of indoor environmental quality (IEQ), along with other factors that exert an influence on physical and psychological aspects of life indoors (e.g., lighting, visual quality, acoustics, and thermal comfort).[4]

Indoor air pollution is a major health hazard in developing countries and is commonly referred to as "household air pollution" in that context.[5] It is mostly relating to cooking and heating methods by burning biomass fuel, in the form of wood, charcoal, dung, and crop residue, in indoor environments that lack proper ventilation. Millions of people, primarily women and children, face serious health risks. In total, about three billion people in developing countries are affected by this problem. The World Health Organization (WHO) estimates that cooking-related indoor air pollution causes 3.8 million annual deaths.[6] The Global Burden of Disease study estimated the number of deaths in 2017 at 1.6 million.[7]

Definition

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For health reasons it is crucial to breathe clean air, free from chemicals and toxicants as much as possible. It is estimated that humans spend approximately 90% of their lifetime indoors[8] and that indoor air pollution in some places can be much worse than that of the ambient air.[9][10]

Various factors contribute to high concentrations of pollutants indoors, ranging from influx of pollutants from external sources, off-gassing by furniture, furnishings including carpets, indoor activities (cooking, cleaning, painting, smoking, etc. in homes to using office equipment in offices), thermal comfort parameters such as temperature, humidity, airflow and physio-chemical properties of the indoor air.[citation needed] Air pollutants can enter a building in many ways, including through open doors or windows. Poorly maintained air conditioners/ventilation systems can harbor mold, bacteria, and other contaminants, which are then circulated throughout indoor spaces, contributing to respiratory problems and allergies.

There have been many debates among indoor air quality specialists about the proper definition of indoor air quality and specifically what constitutes "acceptable" indoor air quality.

Health effects

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Share of deaths from indoor air pollution. Darker colors mean higher numbers.

IAQ is significant for human health as humans spend a large proportion of their time in indoor environments. Americans and Europeans on average spend approximately 90% of their time indoors.[11][12]

The World Health Organization (WHO) estimates that 3.2 million people die prematurely every year from illnesses attributed to indoor air pollution caused by indoor cooking, with over 237 thousand of these being children under 5. These include around an eighth of all global ischaemic heart disease, stroke, and lung cancer deaths. Overall the WHO estimated that poor indoor air quality resulted in the loss of 86 million healthy life years in 2019.[13]

Studies in the UK and Europe show exposure to indoor air pollutants, chemicals and biological contamination can irritate the upper airway system, trigger or exacerbate asthma and other respiratory or cardiovascular conditions, and may even have carcinogenic effects.[14][15][16][17][18][19]

Poor indoor air quality can cause sick building syndrome. Symptoms include burning of the eyes, scratchy throat, blocked nose, and headaches.[20]

Common pollutants

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Generated by indoor combustion

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a 3-stone stove
A traditional wood-fired 3-stone stove in Guatemala, which causes indoor air pollution

Indoor combustion, such as for cooking or heating, is a major cause of indoor air pollution and causes significant health harms and premature deaths. Hydrocarbon fires cause air pollution. Pollution is caused by both biomass and fossil fuels of various types, but some forms of fuels are more harmful than others.

Indoor fire can produce black carbon particles, nitrogen oxides, sulfur oxides, and mercury compounds, among other emissions.[21] Around 3 billion people cook over open fires or on rudimentary cook stoves. Cooking fuels are coal, wood, animal dung, and crop residues.[22] IAQ is a particular concern in low and middle-income countries where such practices are common.[23]

Cooking using natural gas (also called fossil gas, methane gas or simply gas) is associated with poorer indoor air quality. Combustion of gas produces nitrogen dioxide and carbon monixide, and can lead to increased concentrations of nitrogen dioxide throughout the home environment which is linked to respiratory issues and diseases.[24][25]

Carbon monoxide

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One of the most acutely toxic indoor air contaminants is carbon monoxide (CO), a colourless and odourless gas that is a by-product of incomplete combustion. Carbon monoxide may be emitted from tobacco smoke and generated from malfunctioning fuel burning stoves (wood, kerosene, natural gas, propane) and fuel burning heating systems (wood, oil, natural gas) and from blocked flues connected to these appliances.[26] In developed countries the main sources of indoor CO emission come from cooking and heating devices that burn fossil fuels and are faulty, incorrectly installed or poorly maintained.[27] Appliance malfunction may be due to faulty installation or lack of maintenance and proper use.[26] In low- and middle-income countries the most common sources of CO in homes are burning biomass fuels and cigarette smoke.[27]

Health effects of CO poisoning may be acute or chronic and can occur unintentionally or intentionally (self-harm). By depriving the brain of oxygen, acute exposure to carbon monoxide may have effects on the neurological system (headache, nausea, dizziness, alteration in consciousness and subjective weakness), the cardiovascular and respiratory systems (myocardial infarction, shortness of breath, or rapid breathing, respiratory failure). Acute exposure can also lead to long-term neurological effects such as cognitive and behavioural changes. Severe CO poisoning may lead to unconsciousness, coma and death. Chronic exposure to low concentrations of carbon monoxide may lead to lethargy, headaches, nausea, flu-like symptoms and neuropsychological and cardiovascular issues.[28][26]

The WHO recommended levels of indoor CO exposure in 24 hours is 4 mg/m3.[29] Acute exposure should not exceed 10 mg/m3 in 8 hours, 35 mg/m3 in one hour and 100 mg/m3 in 15 minutes.[27]

Secondhand tobacco smoke

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Secondhand smoke is tobacco smoke which affects people other than the 'active' smoker. It is made up of the exhaled smoke (15%) and mostly of smoke coming from the burning end of the cigarette, known as sidestream smoke (85%).[30]

Secondhand smoke contains more than 7000 chemicals, of which hundreds are harmful to health.[30] Secondhand tobacco smoke includes both a gaseous and a particulate materials which, with particular hazards arising from levels of carbon monoxide and very small particulates (fine particulate matter, especially PM2.5 and PM10) which get into the bronchioles and alveoles in the lung.[31] Inhaling secondhand smoke on multiple occasions can cause asthma, pneumonia, lung cancer, and sudden infant death syndrome, among other conditions.[32]

Thirdhand smoke (THS) refers to chemicals that settle on objects and bodies indoors after smoking. Exposure to thirdhand smoke can happen even after the actual cigarette smoke is not present anymore and affect those entering the indoor environment much later. Toxic substances of THS can react with other chemicals in the air and produce new toxic chemicals that are otherwise not present in cigarettes.[33]

The only certain method to improve indoor air quality as regards secondhand smoke is to eliminate smoking indoors.[34] Indoor e-cigarette use also increases home particulate matter concentrations.[35]

Particulates

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Atmospheric particulate matter, also known as particulates, can be found indoors and can affect the health of occupants. Indoor particulate matter can come from different indoor sources or be created as secondary aerosols through indoor gas-to-particle reactions. They can also be outdoor particles that enter indoors. These indoor particles vary widely in size, ranging from nanomet (nanoparticles/ultrafine particles emitted from combustion sources) to micromet (resuspensed dust).[36] Particulate matter can also be produced through cooking activities. Frying produces higher concentrations than boiling or grilling and cooking meat produces higher concentrations than cooking vegetables.[37] Preparing a Thanksgiving dinner can produce very high concentrations of particulate matter, exceeding 300 μg/m3.[38]

Particulates can penetrate deep into the lungs and brain from blood streams, causing health problems such as heart disease, lung disease, cancer and preterm birth.[39]

Generated from building materials, furnishing and consumer products

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Volatile organic compounds

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Volatile organic compounds (VOCs) include a variety of chemicals, some of which may have short- and long-term adverse health effects. There are numerous sources of VOCs indoors, which means that their concentrations are consistently higher indoors (up to ten times higher) than outdoors.[40] Some VOCs are emitted directly indoors, and some are formed through the subsequent chemical reactions that can occur in the gas-phase, or on surfaces.[41][42] VOCs presenting health hazards include benzene, formaldehyde, tetrachloroethylene and trichloroethylene.[43]

VOCs are emitted by thousands of indoor products. Examples include: paints, varnishes, waxes and lacquers, paint strippers, cleaning and personal care products, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions.[44] Chlorinated drinking water releases chloroform when hot water is used in the home. Benzene is emitted from fuel stored in attached garages.

Human activities such as cooking and cleaning can also emit VOCs.[45][46] Cooking can release long-chain aldehydes and alkanes when oil is heated and terpenes can be released when spices are prepared and/or cooked.[45] Leaks of natural gas from cooking appliances have been linked to elevated levels of VOCs including benzene in homes in the USA.[47] Cleaning products contain a range of VOCs, including monoterpenes, sesquiterpenes, alcohols and esters. Once released into the air, VOCs can undergo reactions with ozone and hydroxyl radicals to produce other VOCs, such as formaldehyde.[46]

Health effects include eye, nose, and throat irritation; headaches, loss of coordination, nausea; and damage to the liver, kidney, and central nervous system.[48]

Testing emissions from building materials used indoors has become increasingly common for floor coverings, paints, and many other important indoor building materials and finishes.[49] Indoor materials such as gypsum boards or carpet act as VOC 'sinks', by trapping VOC vapors for extended periods of time, and releasing them by outgassing. The VOCs can also undergo transformation at the surface through interaction with ozone.[42] In both cases, these delayed emissions can result in chronic and low-level exposures to VOCs.[50]

Several initiatives aim to reduce indoor air contamination by limiting VOC emissions from products. There are regulations in France and in Germany, and numerous voluntary ecolabels and rating systems containing low VOC emissions criteria such as EMICODE,[51] M1,[52] Blue Angel[53] and Indoor Air Comfort[54] in Europe, as well as California Standard CDPH Section 01350[55] and several others in the US. Due to these initiatives an increasing number of low-emitting products became available to purchase.

At least 18 microbial VOCs (MVOCs) have been characterised[56][57] including 1-octen-3-ol (mushroom alcohol), 3-Methylfuran, 2-pentanol, 2-hexanone, 2-heptanone, 3-octanone, 3-octanol, 2-octen-1-ol, 1-octene, 2-pentanone, 2-nonanone, borneol, geosmin, 1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, and thujopsene. The last four are products of Stachybotrys chartarum, which has been linked with sick building syndrome.[56]

Asbestos fibers

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Many common building materials used before 1975 contain asbestos, such as some floor tiles, ceiling tiles, shingles, fireproofing, heating systems, pipe wrap, taping muds, mastics, and other insulation materials. Normally, significant releases of asbestos fiber do not occur unless the building materials are disturbed, such as by cutting, sanding, drilling, or building remodelling. Removal of asbestos-containing materials is not always optimal because the fibers can be spread into the air during the removal process. A management program for intact asbestos-containing materials is often recommended instead.

When asbestos-containing material is damaged or disintegrates, microscopic fibers are dispersed into the air. Inhalation of asbestos fibers over long exposure times is associated with increased incidence of lung cancer, mesothelioma, and asbestosis. The risk of lung cancer from inhaling asbestos fibers is significantly greater for smokers. The symptoms of disease do not usually appear until about 20 to 30 years after the first exposure to asbestos.

Although all asbestos is hazardous, products that are friable, e.g. sprayed coatings and insulation, pose a significantly higher hazard as they are more likely to release fibers to the air.[58]

Microplastics

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Microplastic is a type of airborne particulates and is found to prevail in air.[59][60][61][62] A 2017 study found indoor airborne microfiber concentrations between 1.0 and 60.0 microfibers per cubic meter (33% of which were found to be microplastics).[63] Airborne microplastic dust can be produced during renovation, building, bridge and road reconstruction projects[64] and the use of power tools.[65]

Ozone

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Indoors ozone (O3) is produced by certain high-voltage electric devices (such as air ionizers), and as a by-product of other types of pollution. It appears in lower concentrations indoors than outdoors, usually at 0.2-0.7 of the outdoor concentration.[66] Typically, most ozone is lost to surface reactions indoors, rather than to reactions in air, due to the large surface to volume ratios found indoors.[67]

Outdoor air used for ventilation may have sufficient ozone to react with common indoor pollutants as well as skin oils and other common indoor air chemicals or surfaces. Particular concern is warranted when using "green" cleaning products based on citrus or terpene extracts, because these chemicals react very quickly with ozone to form toxic and irritating chemicals[46] as well as fine and ultrafine particles.[68] Ventilation with outdoor air containing elevated ozone concentrations may complicate remediation attempts.[69]

The WHO standard for ozone concentration is 60 μg/m3 for long-term exposure and 100 μg/m3 as the maximum average over an 8-hour period.[29] The EPA standard for ozone concentration is 0.07 ppm average over an 8-hour period.[70]

Biological agents

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Mold and other allergens

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Occupants in buildings can be exposed to fungal spores, cell fragments, or mycotoxins which can arise from a host of means, but there are two common classes: (a) excess moisture induced growth of mold colonies and (b) natural substances released into the air such as animal dander and plant pollen.[71]

While mold growth is associated with high moisture levels,[72] it is likely to grow when a combination of favorable conditions arises. As well as high moisture levels, these conditions include suitable temperatures, pH and nutrient sources.[73] Mold grows primarily on surfaces, and it reproduces by releasing spores, which can travel and settle in different locations. When these spores experience appropriate conditions, they can germinate and lead to mycelium growth.[74] Different mold species favor different environmental conditions to germinate and grow, some being more hydrophilic (growing at higher levels of relative humidity) and other more xerophilic (growing at levels of relative humidity as low as 75–80%).[74][75]

Mold growth can be inhibited by keeping surfaces at conditions that are further from condensation, with relative humidity levels below 75%. This usually translates to a relative humidity of indoor air below 60%, in agreement with the guidelines for thermal comfort that recommend a relative humidity between 40 and 60 %. Moisture buildup in buildings may arise from water penetrating areas of the building envelope or fabric, from plumbing leaks, rainwater or groundwater penetration, or from condensation due to improper ventilation, insufficient heating or poor thermal quality of the building envelope.[76] Even something as simple as drying clothes indoors on radiators can increase the risk of mold growth, if the humidity produced is not able to escape the building via ventilation.[77]

Mold predominantly affects the airways and lungs. Known effects of mold on health include asthma development and exacerbation,[78] with children and elderly at greater risk of more severe health impacts.[79] Infants in homes with mold have a much greater risk of developing asthma and allergic rhinitis.[80][71] More than half of adult workers in moldy or humid buildings suffer from nasal or sinus symptoms due to mold exposure.[71] Some varieties of mold contain toxic compounds (mycotoxins). However, exposure to hazardous levels of mycotoxin via inhalation is not possible in most cases, as toxins are produced by the fungal body and are not at significant levels in the released spores.

Legionella

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Legionnaires' disease is caused by a waterborne bacterium Legionella that grows best in slow-moving or still, warm water. The primary route of exposure is through the creation of an aerosol effect, most commonly from evaporative cooling towers or showerheads. A common source of Legionella in commercial buildings is from poorly placed or maintained evaporative cooling towers, which often release water in an aerosol which may enter nearby ventilation intakes. Outbreaks in medical facilities and nursing homes, where patients are immuno-suppressed and immuno-weak, are the most commonly reported cases of Legionellosis. More than one case has involved outdoor fountains at public attractions. The presence of Legionella in commercial building water supplies is highly under-reported, as healthy people require heavy exposure to acquire infection.

Legionella testing typically involves collecting water samples and surface swabs from evaporative cooling basins, shower heads, faucets/taps, and other locations where warm water collects. The samples are then cultured and colony forming units (cfu) of Legionella are quantified as cfu/liter.

Legionella is a parasite of protozoans such as amoeba, and thus requires conditions suitable for both organisms. The bacterium forms a biofilm which is resistant to chemical and antimicrobial treatments, including chlorine. Remediation for Legionella outbreaks in commercial buildings vary, but often include very hot water flushes (160 °F (71 °C)), sterilisation of standing water in evaporative cooling basins, replacement of shower heads, and, in some cases, flushes of heavy metal salts. Preventive measures include adjusting normal hot water levels to allow for 120 °F (49 °C) at the tap, evaluating facility design layout, removing faucet aerators, and periodic testing in suspect areas.

Other bacteria

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Airborne bacteria

There are many bacteria of health significance found in indoor air and on indoor surfaces. The role of microbes in the indoor environment is increasingly studied using modern gene-based analysis of environmental samples. Currently, efforts are under way to link microbial ecologists and indoor air scientists to forge new methods for analysis and to better interpret the results.[81]

A large fraction of the bacteria found in indoor air and dust are shed from humans. Among the most important bacteria known to occur in indoor air are Mycobacterium tuberculosis, Staphylococcus aureus, Streptococcus pneumoniae.[citation needed]

Virus

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Ninth floor layout of the Metropole Hotel in Hong Kong, showing where an outbreak of the severe acute respiratory syndrome (SARS) occurred

Viruses can also be a concern for indoor air quality. During the 2002–2004 SARS outbreak, virus-laden aerosols were found to have seeped into bathrooms from the bathroom floor drains, exacerbated by the draw of bathroom exhaust fans, resulting in the rapid spread of SARS in Amoy Gardens in Hong Kong.[82][83] Elsewhere in Hong Kong, SARS CoV RNA was found on the carpet and in the air intake vents of the Metropole Hotel, which showed that secondary environmental contamination could generate infectious aerosols and resulted in superspreading events.[84]

Carbon dioxide

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Humans are the main indoor source of carbon dioxide (CO2) in most buildings. Indoor CO2 levels are an indicator of the adequacy of outdoor air ventilation relative to indoor occupant density and metabolic activity.

Indoor CO2 levels above 500 ppm can lead to higher blood pressure and heart rate, and increased peripheral blood circulation.[85] With CO2 concentrations above 1000 ppm cognitive performance might be affected, especially when doing complex tasks, making decision making and problem solving slower but not less accurate.[86][87] However, evidence on the health effects of CO2 at lower concentrations is conflicting and it is difficult to link CO2 to health impacts at exposures below 5000 ppm – reported health outcomes may be due to the presence of human bioeffluents, and other indoor air pollutants related to inadequate ventilation.[88]

Indoor carbon dioxide concentrations can be used to evaluate the quality of a room or a building's ventilation.[89] To eliminate most complaints caused by CO2, the total indoor CO2 level should be reduced to a difference of no greater than 700 ppm above outdoor levels.[90] The National Institute for Occupational Safety and Health (NIOSH) considers that indoor air concentrations of carbon dioxide that exceed 1000 ppm are a marker suggesting inadequate ventilation.[91] The UK standards for schools say that carbon dioxide levels of 800 ppm or lower indicate that the room is well-ventilated.[92] Regulations and standards from around the world show that CO2 levels below 1000 ppm represent good IAQ, between 1000 and 1500 ppm represent moderate IAQ and greater than 1500 ppm represent poor IAQ.[88]

Carbon dioxide concentrations in closed or confined rooms can increase to 1,000 ppm within 45 minutes of enclosure. For example, in a 3.5-by-4-metre (11 ft × 13 ft) sized office, atmospheric carbon dioxide increased from 500 ppm to over 1,000 ppm within 45 minutes of ventilation cessation and closure of windows and doors.[93]

Radon

[edit]

Radon is an invisible, radioactive atomic gas that results from the radioactive decay of radium, which may be found in rock formations beneath buildings or in certain building materials themselves.

Radon is probably the most pervasive serious hazard for indoor air in the United States and Europe. It is a major cause of lung cancer, responsible for 3–14% of cases in countries, leading to tens of thousands of deaths.[94]

Radon gas enters buildings as a soil gas. As it is a heavy gas it will tend to accumulate at the lowest level. Radon may also be introduced into a building through drinking water particularly from bathroom showers. Building materials can be a rare source of radon, but little testing is carried out for stone, rock or tile products brought into building sites; radon accumulation is greatest for well insulated homes.[95] There are simple do-it-yourself kits for radon gas testing, but a licensed professional can also check homes.

The half-life for radon is 3.8 days, indicating that once the source is removed, the hazard will be greatly reduced within a few weeks. Radon mitigation methods include sealing concrete slab floors, basement foundations, water drainage systems, or by increasing ventilation.[96] They are usually cost effective and can greatly reduce or even eliminate the contamination and the associated health risks.[citation needed]

Radon is measured in picocuries per liter of air (pCi/L) or becquerel per cubic meter (Bq m-3). Both are measurements of radioactivity. The World Health Organization (WHO) sets the ideal indoor radon levels at 100 Bq/m-3.[97] In the United States, it is recommend to fix homes with radon levels at or above 4 pCi/L. At the same time it is also recommends that people think about fixing their homes for radon levels between 2 pCi/L and 4 pCi/L.[98] In the United Kingdom the ideal is presence of radon indoors is 100 Bq/m-3. Action needs to be taken in homes with 200 Bq/m−3 or more.[99]

Interactive maps of radon affected areas are available for various regions and countries of the world.[100][101][102]

IAQ and climate change

[edit]

Indoor air quality is linked inextricably to outdoor air quality. The Intergovernmental Panel on Climate Change (IPCC) has varying scenarios that predict how the climate will change in the future.[103] Climate change can affect indoor air quality by increasing the level of outdoor air pollutants such as ozone and particulate matter, for example through emissions from wildfires caused by extreme heat and drought.[104][105] Numerous predictions for how indoor air pollutants will change have been made,[106][107][108][109] and models have attempted to predict how the forecasted IPCC scenarios will vary indoor air quality and indoor comfort parameters such as humidity and temperature.[110]

The net-zero challenge requires significant changes in the performance of both new and retrofitted buildings. However, increased energy efficient housing will trap pollutants inside, whether produced indoors or outdoors, and lead to an increase in human exposure.[111][112]

Indoor air quality standards and monitoring

[edit]

Quality guidelines and standards

[edit]

For occupational exposure, there are standards, which cover a wide range of chemicals, and applied to healthy adults who are exposed over time at workplaces (usually industrial environments).These are published by organisations such as Occupational Safety and Health Administration (OSHA), the National Institute for Occupational Safety and Health (NIOSH), the UK Health and Safety Executive (HSE).

There is no consensus globally about indoor air quality standards, or health-based guidelines. However, there are regulations from some individual countries and from health organisations. For example, the World Health Organization (WHO) has published health-based global air quality guidelines for the general population that are applicable both to outdoor and indoor air,[29] as well as the WHO IAQ guidelines for selected compounds,[113] whereas the UK Health Security Agency published IAQ guidelines for selected VOCs.[114] The Scientific and Technical Committee (STC34) of the International Society of Indoor Air Quality and Climate (ISIAQ) created an open database that collects indoor environmental quality guidelines worldwide.[115] The database is focused on indoor air quality (IAQ), but is currently extended to include standards, regulations, and guidelines related to ventilation, comfort, acoustics, and lighting.[116][117]

Real-time monitoring

[edit]

Since indoor air pollutants can adversely affect human health, it is important to have real-time indoor air quality assessment/monitoring system that can help not only in the improvement of indoor air quality but also help in detection of leaks, spills in a work environment and boost energy efficiency of buildings by providing real-time feedback to the heating, ventilation, and air conditioning (HVAC) system(s).[118] Additionally, there have been enough studies that highlight the correlation between poor indoor air quality and loss of performance and productivity of workers in an office setting.[119]  

Combining the Internet of Things (IoT) technology with real-time IAQ monitoring systems has  tremendously gained momentum and popularity as interventions can be done based on the real-time sensor data and thus help in the IAQ improvement.[120]   

Improvement measures

[edit]

Indoor air quality can be addressed, achieved or maintained during the design of new buildings or as mitigating measures in existing buildings. A hierarchy of measures has been proposed by the Institute of Air Quality Management. It emphasises removing pollutant sources, reducing emissions from any remaining sources, disrupting pathways between sources and the people exposed, protecting people from exposure to pollutants, and removing people from areas with poor air quality.[121]

A report assisted by the Institute for Occupational Safety and Health of the German Social Accident Insurance can support in the systematic investigation of individual health problems arising at indoor workplaces, and in the identification of practical solutions.[122]

Source control

[edit]

HVAC design

[edit]

Environmentally sustainable design concepts include aspects of commercial and residential heating, ventilation and air-conditioning (HVAC) technologies. Among several considerations, one of the topics attended to is the issue of indoor air quality throughout the design and construction stages of a building's life.[citation needed]

One technique to reduce energy consumption while maintaining adequate air quality, is demand-controlled ventilation. Instead of setting throughput at a fixed air replacement rate, carbon dioxide sensors are used to control the rate dynamically, based on the emissions of actual building occupants.[citation needed]

One way of quantitatively ensuring the health of indoor air is by the frequency of effective turnover of interior air by replacement with outside air. In the UK, for example, classrooms are required to have 2.5 outdoor air changes per hour. In halls, gym, dining, and physiotherapy spaces, the ventilation should be sufficient to limit carbon dioxide to 1,500 ppm. In the US, ventilation in classrooms is based on the amount of outdoor air per occupant plus the amount of outdoor air per unit of floor area, not air changes per hour. Since carbon dioxide indoors comes from occupants and outdoor air, the adequacy of ventilation per occupant is indicated by the concentration indoors minus the concentration outdoors. The value of 615 ppm above the outdoor concentration indicates approximately 15 cubic feet per minute of outdoor air per adult occupant doing sedentary office work where outdoor air contains over 400 ppm[123] (global average as of 2023). In classrooms, the requirements in the ASHRAE standard 62.1, Ventilation for Acceptable Indoor Air Quality, would typically result in about 3 air changes per hour, depending on the occupant density. As the occupants are not the only source of pollutants, outdoor air ventilation may need to be higher when unusual or strong sources of pollution exist indoors.

When outdoor air is polluted, bringing in more outdoor air can actually worsen the overall quality of the indoor air and exacerbate some occupant symptoms related to outdoor air pollution. Generally, outdoor country air is better than indoor city air.[citation needed]

The use of air filters can trap some of the air pollutants. Portable room air cleaners with HEPA filters can be used if ventilation is poor or outside air has high level of PM 2.5.[122] Air filters are used to reduce the amount of dust that reaches the wet coils.[citation needed] Dust can serve as food to grow molds on the wet coils and ducts and can reduce the efficiency of the coils.[citation needed]

The use of trickle vents on windows is also valuable to maintain constant ventilation. They can help prevent mold and allergen build up in the home or workplace. They can also reduce the spread of some respiratory infections.[124]

Moisture management and humidity control requires operating HVAC systems as designed. Moisture management and humidity control may conflict with efforts to conserve energy. For example, moisture management and humidity control requires systems to be set to supply make-up air at lower temperatures (design levels), instead of the higher temperatures sometimes used to conserve energy in cooling-dominated climate conditions. However, for most of the US and many parts of Europe and Japan, during the majority of hours of the year, outdoor air temperatures are cool enough that the air does not need further cooling to provide thermal comfort indoors.[citation needed] However, high humidity outdoors creates the need for careful attention to humidity levels indoors. High humidity give rise to mold growth and moisture indoors is associated with a higher prevalence of occupant respiratory problems.[citation needed]

The "dew point temperature" is an absolute measure of the moisture in air. Some facilities are being designed with dew points in the lower 50s °F, and some in the upper and lower 40s °F.[citation needed] Some facilities are being designed using desiccant wheels with gas-fired heaters to dry out the wheel enough to get the required dew points.[citation needed] On those systems, after the moisture is removed from the make-up air, a cooling coil is used to lower the temperature to the desired level.[citation needed]

Commercial buildings, and sometimes residential, are often kept under slightly positive air pressure relative to the outdoors to reduce infiltration. Limiting infiltration helps with moisture management and humidity control.

Dilution of indoor pollutants with outdoor air is effective to the extent that outdoor air is free of harmful pollutants. Ozone in outdoor air occurs indoors at reduced concentrations because ozone is highly reactive with many chemicals found indoors. The products of the reactions between ozone and many common indoor pollutants include organic compounds that may be more odorous, irritating, or toxic than those from which they are formed. These products of ozone chemistry include formaldehyde, higher molecular weight aldehydes, acidic aerosols, and fine and ultrafine particles, among others. The higher the outdoor ventilation rate, the higher the indoor ozone concentration and the more likely the reactions will occur, but even at low levels, the reactions will take place. This suggests that ozone should be removed from ventilation air, especially in areas where outdoor ozone levels are frequently high.

Effect of indoor plants

[edit]
Spider plants (Chlorophytum comosum) absorb some airborne contaminants.

Houseplants together with the medium in which they are grown can reduce components of indoor air pollution, particularly volatile organic compounds (VOC) such as benzene, toluene, and xylene. Plants remove CO2 and release oxygen and water, although the quantitative impact for house plants is small. The interest in using potted plants for removing VOCs was sparked by a 1989 NASA study conducted in sealed chambers designed to replicate the environment on space stations. However, these results suffered from poor replication[125] and are not applicable to typical buildings, where outdoor-to-indoor air exchange already removes VOCs at a rate that could only be matched by the placement of 10–1000 plants/m2 of a building's floor space.[126]

Plants also appear to reduce airborne microbes and molds, and to increase humidity.[127] However, the increased humidity can itself lead to increased levels of mold and even VOCs.[128]

Since extremely high humidity is associated with increased mold growth, allergic responses, and respiratory responses, the presence of additional moisture from houseplants may not be desirable in all indoor settings if watering is done inappropriately.[129]

Institutional programs

[edit]
EPA graphic about asthma triggers

The topic of IAQ has become popular due to the greater awareness of health problems caused by mold and triggers to asthma and allergies.

In the US, the Environmental Protection Agency (EPA) has developed an "IAQ Tools for Schools" program to help improve the indoor environmental conditions in educational institutions. The National Institute for Occupational Safety and Health conducts Health Hazard Evaluations (HHEs) in workplaces at the request of employees, authorized representative of employees, or employers, to determine whether any substance normally found in the place of employment has potentially toxic effects, including indoor air quality.[130]

A variety of scientists work in the field of indoor air quality, including chemists, physicists, mechanical engineers, biologists, bacteriologists, epidemiologists, and computer scientists. Some of these professionals are certified by organizations such as the American Industrial Hygiene Association, the American Indoor Air Quality Council and the Indoor Environmental Air Quality Council.

In the UK, under the Department for Environment Food and Rural Affairs, the Air Quality Expert Group considers current knowledge on indoor air quality and provides advice to government and devolved administration ministers.[131]

At the international level, the International Society of Indoor Air Quality and Climate (ISIAQ), formed in 1991, organizes two major conferences, the Indoor Air and the Healthy Buildings series.[132]

See also

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Sources

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Monographs
Articles, radio segments, web pages

Further reading

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A Nest Labs thermostat

Smart thermostats are Wi-Fi thermostats that can be used with home automation and are responsible for controlling a home's heating, ventilation, and air conditioning. They perform similar functions as a programmable thermostat as they allow the user to control the temperature of their home throughout the day using a schedule, but also contain additional features, such as Wi-Fi connectivity,[1][2] that improve upon the issues with programming.

Like other Wi-Fi thermostats, they are connected to the Internet via a Wi-Fi network. They allow users to adjust heating settings from other internet-connected devices, such as a laptop or smartphones. This allows users to control the thermostat remotely. This ease of use is essential for ensuring energy savings: studies have shown that households with programmable thermostats actually have higher energy consumption than those with simple thermostats because residents program them incorrectly or disable them completely.[3][4]

Smart thermostats also record internal/external temperatures, the time the HVAC system has been running and can notify the user if the system's air filter needs to be replaced. This information is typically displayed later on an internet-connected device such as a smartphone.

Manual vs. programmable vs. smart thermostats

[edit]

Manual thermostats

[edit]
Honeywell Manual Thermostat

Manual thermostats (also known as analog thermostats) are the oldest and simplest type of thermostats. These thermostats are set to one temperature and do not change until the user manually adjusts the temperature.[5]

Programmable thermostats

[edit]

Programmable thermostats, first introduced over 100 years ago,[6] are a type of thermostat that allows the user to set a schedule for different temperatures at different times. Most programmable thermostats also have a hold feature which suspends the schedule and effectively turns the thermostat into a manual thermostat.[5] The idea of the scheduling feature is that users will set a warmer or cooler temperature when the home is unoccupied to save energy and money. Due to this assumed energy savings, some building codes and government programs began requiring the use of programmable thermostats.[7] Due to the way people use these devices, most programmable thermostats result in more energy use than the basic manual thermostat.[8]

Issues with programmable thermostats

[edit]

One of the main objectives of smart thermostats is to reduce the issues involved with using traditional programmable thermostats. In order to understand how smart thermostats take on this task, it is important to understand the issues regarding programmable thermostats and how they affect energy consumption. Between 2008-2009, Florida Power & Light (FPL) provided 400 homeowners with programmable thermostats and monitored their heating and cooling patterns. Out of the 400 participants, 56% of users used the programming feature while the remaining participants did not program the thermostat and left it on "hold". It was determined that the users who used the programming feature actually consumed 12% more energy than the non-programmers. This consumption increase resulted from higher overnight duty cycles associated with lower thermostat setpoints (i.e. lower temperature setting), due to confusion with setting the schedule. This study reveals that programmable thermostats will not necessarily save energy. The smart thermostat attempts to combat this issue by taking the user out of the picture and relying on sensors and computers to save energy.[8]

Another study conducted on the issue determined that the biggest problem for programmable thermostats was the human using it. The technology inside a programmable thermostat is no doubt one of the most important factors in determining whether or not the thermostat will be successful in saving energy. But an equally important factor is the human who is using the thermostat. Unfortunately, many people who own programmable thermostats do not know how to use the thermostat or are not using all of the features that are offered. One study conducted a number of interviews, surveys, and observations to determine that the vast majority of programmable thermostat owners are not using the thermostats for their intended purpose. An online survey showed that 89% of respondents do not use the schedule feature on their programmable thermostat. Other results from the interviews and surveys show that a large number of people have misconceptions about heating/cooling and the use of programmable thermostats. One misconception is people believing that heating all of the time is more efficient than scheduling the heat to turn off. Another misconception noted in the study is that turning down the thermostat does not substantially reduce energy consumption. These misconceptions reaffirm the idea that the programmable thermostat itself could have all of the necessary tools, but if the user does not use them or uses them incorrectly, then these thermostats will fail at saving energy.[7]

As a result of these studies and others like them, energy star suspended its labelling of programmable thermostats in December 2009. It became the goal of smart thermostats to address these issues by taking the human out of the picture and creating a thermostat that uses smart computing to truly reduce energy usage and cost.[7][8]

Smart thermostats

[edit]

Smart thermostats are similar to programmable thermostats in the sense that they have a scheduling feature that allows users to set different temperatures for different times of the day. In addition to this feature, smart thermostats implement other technologies to reduce the amount of human error involved with using programmable thermostats. Smart thermostats incorporate the use of sensors that determine whether or not the home is occupied and can suspend heating or cooling until the occupant returns. Additionally, smart thermostats utilize Wi-Fi connectivity to give the user access to the thermostat at all times. These additional technologies have proven to make smart thermostats successful in saving users energy and money.[5]

History

[edit]

Development of the smart thermostat began in 2007 with the creation of the ecobee thermostat. The founder of ecobee, Stuart Lombard, wanted to save energy and reduce his family's carbon footprint. After realizing that heating and cooling made up most of his home's energy usage,[9] Lombard purchased a programmable thermostat in an attempt to reduce total energy usage. Lombard quickly discovered that the programmable thermostat was difficult to use and unreliable. Following difficulties with the programmable thermostat, he set out to create a smart thermostat that saved energy and was easy to use. With that goal, the ecobee company was created in attempt to offer users a thermostat that could truly save energy by fixing the issues with programmable thermostats.[10]

Following the ecobee, EnergyHub released its version of a smart thermostat in 2009 with the creation of the EnergyHub Dashboard. The co-founder of EnergyHub, Seth Frader-Thompson, got the idea for the Dashboard from his Prius. The Prius had screens on the dashboard that displayed the car's gas mileage in real time. Thompson felt that a house should have something that does the same. With that goal in mind, Thompson created a thermostat that could communicate with a home's furnace and appliances to determine the energy usage and efficiency and how much it was costing. The thermostat also had the capability to turn off appliances or raise and lower the temperature to save energy and cost. Ultimately, the goal of this thermostat was to display energy usage to users and to save energy and money.[11]

Nest Labs company logo. Creators of the Nest Learning Thermostat.

In 2011, Nest Labs developed the Nest Learning Thermostat. The Nest Thermostat attempted to reduce home energy consumption by addressing the problems with programmable thermostats through the use of better technology. This new technology included the implementation of sensors, algorithms, machine learning, and cloud computing. These technologies learn the behaviors and preferences of the occupants, and adjust the temperature up or down to make the occupant comfortable when they are home and to save energy when they are away. Additionally, the Nest Thermostat connects to the home Wi-Fi. This allows users to change the temperature, adjust the schedule, and check energy usage from a smartphone or laptop. All of these features were part of Nest's goal to create an easy to use thermostat that saves users energy and money.[12]

Technology

[edit]

Programmable schedule and auto schedule

[edit]

The programmable schedule feature on the smart thermostat is similar to that on standard programmable thermostats. Users are given the option to program a custom schedule to reduce energy usage when they are away from the home. Studies have shown, though, that manually creating a schedule may lead to more energy usage than just keeping the thermostat at a set temperature.[8] To avoid this problem, smart thermostats also provide an auto schedule feature. This feature requires the use of algorithms and pattern recognition to create a schedule that results in occupant comfort and energy savings. Upon creating a schedule, the thermostat will continue monitoring occupant behavior to make changes to the auto schedule. By taking the human error out of the scheduling, smart thermostats can create smart schedules that actually save energy.[13]

Sensor

[edit]
The Nest Web Portal allows users to remotely change the temperature, create a schedule, and view past energy usage.

In an attempt to mitigate the issues with human error involved with programmable thermostats, the smart thermostat utilizes a sensor that can determine occupancy patterns to automatically change the temperature based on occupant patterns and behaviors. The Nest Learning Thermostat in particular uses passive infrared (PIR) motion sensors inside the unit to sense occupancy in the vicinity of the thermostat. This sensor informs the thermostat whether or not the home is occupied. In the case that the home is not occupied, the thermostat can suspend heating/cooling until the sensor is reactivated by an occupant. This sensor is also used to determine the occupancy patterns to create the auto schedule. A grille member is placed in front of the sensor to visually conceal and protect the PIR motion sensor inside the thermostat. The grille also helps to make the thermostat visually pleasing.[2] While this sensor technology is important for conserving energy, it is not without flaws. One of the major issues is that the sensor must be activated by someone walking in front of or near the thermostat. It is possible that an occupant could be at home and not pass in front of the sensor. In this case, the thermostat would shut off the heating/cooling and decrease human comfort.[14]

Wi-Fi connection

[edit]

A major feature of Wi-Fi thermostats (such as smart thermostats) is their ability to connect to the internet. These thermostats are designed with a Wi-Fi module that allows the thermostat to connect to the user's home or office network and interface with a web portal or smartphone application, allowing users to control the thermostat remotely.[15] The Wi-Fi feature also has the ability to send reports on energy usage and HVAC system performance via the web portal, informing the user on their energy efficiency and how it compares to other smart thermostat users. It also may alert users when a problem arises with their HVAC system or when it is time for equipment maintenance. The thermostat also may use the Wi-Fi connection to display current weather conditions and the weather forecast.[1]

Another feature offered by some smart thermostats through the internet connection is geofencing. A geofence is a perimeter boundary created around the location of a smartphone or other device, based on GPS signals. The benefit of having a smart thermostat with geofencing capabilities is that it uses a users smartphone location to determine whether the home is occupied. Instead of using a schedule or sensor to determine occupancy, the smart thermostat can rely on the location of the geofence to tell the HVAC system whether it needs to be on or off.[16] Since most people carry their phones with them, geofencing can be an accurate way to determine occupancy patterns.[13]

Learning thermostats

[edit]
The Ecobee 4 thermostat

Some smart thermostats, such as the Nest thermostat, can learn when the house is likely to be occupied, and when it is likely to be empty. This allows automatic pre-heating or pre-cooling so the temperature is comfortable when a resident arrives. If the residents or lifestyles change, these smart thermostats will gradually adjust the schedule, maintaining energy savings and comfort.

Motion detectors can determine if someone is home. One smart thermostat that uses motion detectors is the Ecobee4.[17]

A wireless network can be used to sense when someone is out of range, thus determining if they're in or nearby their home. This geofencing technique is used by the Honeywell T6 Smart Thermostat.

Connected thermostats

[edit]

A Connected thermostat is one that can be controlled through an internet connection, but will not provide analytic information. In recent years Wi-Fi thermostats have risen in popularity, they combine the technology of thermometers and Wi-Fi. So now you can have a thermometer in your home that is displayed on your phone that uses Wi-Fi technology. This technology is being developed right now so it will be available for thermostats in machinery and cars. Google is involved in this push towards technology since it acquired a Wi-Fi temperature company called Nest.[18] The market of smart thermostats is expected to reach around 3.5 Billion USD by the end of the year 2022.[citation needed]

Zoned systems

[edit]

Rather than controlling the temperature of the whole house, zoned systems can control individual rooms. This can increase energy savings, for example by heating or cooling only a Home-office and not the bedrooms and other areas that are empty during the day.

Studies

[edit]

Internal studies

[edit]

To show that their thermostats save energy and money, numerous smart thermostat producers have conducted models and studies to confirm their savings claims. One popular way that smart thermostat producers calculate energy usage is through energy modeling. In these models, the smart thermostat is compared to a thermostat set at a constant temperature, and savings are calculated. Using this method, ecobee calculated energy savings by correlating how long heating and cooling equipment run to local weather conditions. Energy savings were calculated relative to a constant temperature of 22 °C (72 °F). Upon conducting this model, ecobee determined a 23% savings on heating and cooling costs for those who switch to their smart thermostat.[19] Using a similar modeling method, Nest claimed a 20% energy savings for homeowners who install a Nest Learning Thermostat.[20]

To determine energy savings using actual data instead of energy models, in February 2015, Nest conducted a national study of Nest customers in 41 states who had enrolled in Nest's MyEnergy service. In May 2013, Nest acquired MyEnergy, a company that tracks and analyzes utility usage of people enrolled in the program. Upon acquiring MyEnergy, Nest was able to use the historical data to determine the energy savings of those who installed the Nest Learning Thermostat. This study looked at energy usage before and after the installation of a Nest Learning Thermostat and used a weather normalization procedure to prevent unusually cold or warm weather from skewing the data. The study had a sample size of 735 homes for gas usage analysis and 624 homes for electrical analysis. All of these homes were enrolled in the MyEnergy program and had sufficient energy data before and after the installation of a Nest Learning Thermostat. After observing the energy usage for one year, Nest determined that there was an average gas savings of 10% and a cooling savings of 17.5%. The savings varied from house to house depending on how occupants set their thermostat before the installation of a Nest thermostat, along with differences in occupancy patterns, house characteristics, and weather.[20]

Gas and Electric Savings Results[20]
Fuel Sample Size Pre-Nest Total Energy Use Pre-Nest HVAC Total Energy Savings % of HVAC
Natural Gas (therms/yr) 735 774 584 56 ±12 9.6 ±2.1%
Electricity (kWh/yr) 624 12,355 3,351 585 ±97 17.5 ±2.9%

While the results from the MyEnergy study are significantly lower than those from energy modeling, both show a savings in energy usage by switching to a smart thermostat.[19][20]

Third-party studies

[edit]

Since the release of smart thermostats, a number of third party studies have been conducted to determine if smart thermostats actually save energy and how they compare to manual and programmable thermostats with regards to savings. One study conducted an experiment in which 300 standard programmable thermostats were placed in homes and 300 Nest smart thermostats were placed in other homes. It is important to note that the homeowners involved in this study received proper training on how to properly use all of the thermostat functions. This effectively eliminated the issues regarding human error with programmable thermostats. All homes were located within one region of Indiana and had previously undergone home energy assessment. After 1 year of observation, the study concluded that Nest users reduced their heating gas consumption by 12.5% while users of a standard programmable thermostat reduced consumption by 5%. Additionally, it was concluded that Nest and standard programmable thermostat users reduced their cooling electric consumption by 13.9% and 13.1%, respectively. The major factors that allowed Nest to reduce consumption more than other thermostats was its ability to further reduce human error and set more efficient temperatures. The Nest thermostat used sensors and Wi-Fi connectivity to adjust the temperature on its own and provide more savings. This study helps to suggest that smart thermostats are in fact successful in reducing energy consumption.[21]

Gas Savings as a Percentage of Heating Gas Usage[21]
Thermostat Pre Heating

Usage (Therms)

Savings

(Therms)

Savings

(%)

Range of

Savings (Therms)

Range of

Savings (%)

Nest 548 69 12.5% 60 to 77 11 to 14%
Programmable 602 30 5% 22 to 38 4 to 6%
Electric Savings as a Percentage of Cooling Electricity Usage[21]
Thermostat Pre Usage

(kWh)

Savings

(kWh)

Savings

(%)

Range of

Savings (kWh)

Range of

Savings (%)

Nest 3,080 429 13.9% 270 to 589 9 to 19%
Programmable 2,537 332 13.1% 181 to 483 7 to 19%

A similar study conducted in 2012 with the ecobee thermostat also concluded that smart thermostats are capable of saving energy. The goal of this pilot program was to determine the gas and electric savings of smart thermostats. This study provided 86 households with 123 ecobee thermostats and monitored the homes for 12 months. The study included 69 houses from Massachusetts and 17 from Rhode Island. The participants either had manual or programmable thermostats before the study was conducted. Gas and electric billing data were provided for 12 months before the study was conducted to use as a baseline. After the 12 months of observation, the study concluded that ecobee thermostats led to an average electricity savings of 16% and an average gas savings of 10%. The gas savings for manual thermostat replacements (10% per thermostat) was found to be larger than for programmable thermostat replacements (8% per thermostat). The difference in electricity savings between homes whose prior equipment was a manual thermostat or programmable thermostat was found to be minimal.[1]

Gas Billing Analysis Savings Summary[1]
Previous

Thermostat

Number of

Participants

Pre Usage

(Therms)

Savings

(Therms)

Savings

(%)

Range of

Savings (Therms)

Range of

Savings (%)

Manual

Thermostat

23 890 87 10% 60 to 113 7 to 13%
Programmable

Thermostat

44 842 66 8% 43 to 88 5 to 10%
Electric Savings Analysis Savings Summary[1]
Previous

Thermostat

Number of

Participants

Pre Usage

(kWh)

Savings

(kWh)

Savings

(%)

Manual and

Programmable

Thermostat

12 640 113 16%

Although these studies report differing amounts of savings compared to the internal studies conducted by Nest and ecobee, both of these studies show that smart thermostats have the potential to save energy. This suggests that the technologies added to fix the issues with programmable thermostats have been successful.[1][21]

Study discrepancies

[edit]

Although most studies show that smart thermostats show an energy savings, the amount of savings varies. A large discrepancy is seen between energy modeling savings and the savings found using actual data. The energy modeling compares the smart thermostat to a constant set point temperature of 72 °F, but an online survey conducted by Nest showed that most users have a set point temperature that is 10% more efficient.[20] Therefore, the savings predicted by the energy modeling are going to be higher than real savings.

There are other factors that cause discrepancies even between studies that all look at actual data. Most studies compare total energy consumption of a house from year to year to determine energy savings, as opposed to looking at just the energy that is used for heating and cooling. Due to this, there could be other factors that change the energy consumption of a house, and it might be incorrect to state that the thermostat is responsible for all energy savings in a house. For example, it is possible that other new energy efficient practices/appliances are partially responsible for the savings in addition to the thermostat.[20]

Another discrepancy to consider is the population of people involved in the study. Some studies, such as the MyEnergy study, involve people who signed up for an energy analysis program.[20] These people are likely to be more energy conscious and efficient and have better heating and cooling practices. This greater interest in energy efficiency may lead to lower energy savings by switching to a smart thermostat. The most energy-conscious customers are the ones more likely to have had efficient thermostat settings, therefore, the savings that they receive from the smart thermostat may not be as great.[1]

The weather will also have an impact on the results of a study. Having very high temperatures in the summer and very cold temperatures in the winter will lead to more cooling and heating in those months, requiring more energy. When comparing year to year data, if one year had extreme temperatures, while the following year had moderate temperatures, the savings may look drastic. In reality though, the savings are not from the thermostat, but rather from the change in weather. Studies will try to mitigate this problem through weather normalization procedures.[20]

Broader Impact

[edit]

While smart thermostats have the potential to save energy consumption, they can create unintended consequences on the broader electrical grid. Smart thermostats tend to operate similarly across a population and can create load synchronization. This load synchronization can create much higher peaks and more rapid changes in heating demand. Particularly in the winter, this heating demand is shifted earlier in the morning, when solar electricity is unavailable, making it more difficult to supply electric heating sources like heat pumps with renewable energy.[22]

Improvements

[edit]

Motion sensors

[edit]

One issue with using a smart thermostat is the unreliability of the motion sensor. One of the main features of the smart thermostat is the ability to change the temperature when the sensor in the thermostat does not sense an occupant. The only sensor that is used though is the sensor in the thermostat. This means that if the home is occupied but no one walks passed the thermostat, the thermostat will think that the home is unoccupied and will change the temperature, potentially leading to occupant discomfort.

One study attempted to address this issue by adding more sensors throughout the house. Instead of using just one sensor in the thermostat, this team experimented with placing motion sensors and door sensors throughout the house to gain better understanding of the occupant's sleeping and occupancy patterns. These sensors communicated with each other and used an algorithm to quickly determine whether the occupants were active, sleeping, or away. The system used historical data to estimate when occupants would be returning and would begin "preheating" the home before they arrived. Additionally, the system would drift further from the set point when it was certain that no one was home. The study compared a standard ("reactive") smart thermostat and the multiple sensor system to a manual thermostat. The study concluded that a reactive smart thermostat with just on sensor saves, on average, 6.8% of energy consumption, while the multiple sensor system saved an average of 28% of energy consumption. This study again shows that, on average, smart thermostats achieve their goal of saving energy. It also shows that smart thermostats are not as well developed as they could be, and the addition of more sensors could result in better performance and energy savings.[14]

User interface

[edit]

One of the issues with programmable thermostats that smart thermostats try to fix is the confusing user interface. Many owners of programmable thermostats found the controls and directions to be too confusing and opted out of using the scheduling feature completely. Others who used the feature used it incorrectly, due to the confusing directions, and saw an increase in energy usage.[7] Developers of smart thermostats have attempted to fix this issue by creating simple to use thermostats and providing proper direction. While this is an improvement on programmable thermostats, studies have shown that users desire more intense training from the installer of the thermostat on how to use the technical features. Additionally, many smart thermostats use a web portal where users can adjust the thermostat settings and look at their energy usage history. Again, studies have shown that users want this feature to be improved. Some complain that the web portal is not user friendly and they desire more training on how to use the web features during installation.[1]

Internet security

[edit]

Researchers from the University of Central Florida conducted an experiment to show that hackers could use the Nest thermostat as an entry point into one's home. Upon being connected to the internet, the hackers could use the thermostat to control local network traffic from a remote location. The hacker could also use the thermostat to act as a spy and would know whether or not the home is occupied. The research showed that in order for a hacker to gain access to the thermostat, they would have to gain physical access to the device and upload the malicious firmware via a USB port. This drastically decreases the chances that this type of attack will occur, but it is still possible if a used thermostat is purchased with the firmware already uploaded. The problem that allows this type of attack is with the hardware in the thermostat. Therefore, Nest cannot repair this issue with a simple software update, but rather it would need to build a new thermostat that can prevent this type of attack.[15][23]

Sustainability

[edit]
Residential Energy Consumption Survey conducted by the U.S. Energy Information Administration shows residential electricity consumption by category.

Climate change

[edit]

According to the 2015 Residential Energy Consumption Survey conducted by the U.S. Energy Information Administration, home heating and cooling account for the highest percentage of residential electrical energy consumption. Air conditioning accounts for 17% of electrical usage while space heating accounts for 15%.[9] The Residential Energy Consumption Survey from 2009 looked at energy consumption from all energy types (natural gas and electricity). This survey determined that space heating accounted for 42% of all residential energy consumption, while air conditioning accounted for 6%.[24] This energy usage needed to heat and cool homes is directly linked to climate change, as the energy provided for heating and cooling often comes from the burning of fossil fuels, leading to the release of greenhouse gas emissions. With an added focus on combating climate change and global warming, nations from around the world have begun to take on this issue by limiting greenhouse gas emissions and preventing the rise in global temperature through agreements such as The Paris Agreement.[25] Any steps taken to reduce residential energy consumption will help to achieve those goals.

Smart thermostats could be a solution to reducing energy consumption, as numerous studies have shown that these thermostats do in fact reduce home energy consumption.[1][19][20][21] Additionally, the technology within smart thermostats has proven to provide optimal occupant comfort, while still reducing energy consumption.[20] In addition to providing comfort, these technologies take the human out of the picture. Many sustainable devices rely heavily on how the user uses them. By relying on technology instead of human actions, smart thermostats reduce the amount of human error often experienced with other sustainable devices, such as the programmable thermostat. These factors suggest that installing a smart thermostat is one easy step than many people can take to reduce energy usage and greenhouse gas emissions, ultimately leading to a more sustainable future.

Programs

[edit]

Many housing corporations and smart thermostat developers realize the potential of smart thermostats to save energy, and have developed programs to advance sustainability through smarter technology. Ecobee promotes a sustainable future through its "A Better Tomorrow" program, in which the company donates time, data, and technology to ensure a brighter future.[26] As part of this program, in January 2018, ecobee donated 776 ecobee thermostats to the Toronto Community Housing Corporation (TCHC) to help the city of Toronto advance their climate change action plan. This donation helps to improve the TCHC's goal of providing healthy, safe, and sustainable homes for the people of Toronto.[27]

Another popular way that utility companies promote switching to a smart thermostat is through monetary incentives. The San Diego Gas & Electric company currently runs a program that offers participants a $50 e-gift card after switching to a smart thermostat.[28] The Wisconsin Focus on Energy program partners with utility companies across Wisconsin to offer a $75 check to those who purchase a qualifying smart thermostat.[29] Austin Energy, a utility company providing electricity to the city of Austin, Texas, offers a $25 rebate for each eligible smart thermostat that is purchased and installed.[30] Pacific Gas and Electric Company (PG&E) offers smart thermostat rebates in California for residential and multifamily customers.[31][32] Many other companies across the United States offer similar programs to incentive smart thermostats and more sustainable heating and cooling.[33][34]

Upon installing a smart thermostat, there are additional programs that continue to promote sustainability and reduced energy consumption. The Nest Rush Hour Rewards program partners with utility companies across the United States to incentivize customers to set a higher or lower temperature during peak demand periods. Energy rush hours occur when everyone in a particular area turns on their heating or cooling at the same time, such as during a heat wave. This extra demand may require utility companies to run additional power plants, leading to more cost and carbon emissions. To avoid this, the Rush Hour Rewards program incentivizes customers to set a more efficient temperature that will reduce the amount of energy needed to be produced by the utility.[35]

As more programs like these are created, smart thermostats will play an increasingly important role in reducing residential energy consumption. This reduction will lead to fewer greenhouse gas emissions, helping to create a more sustainable future.

See also

[edit]

References

[edit]
  1. ^ a b c d e f g h i Miller, Alexi, et al. Wi-Fi Programmable Controllable Thermostat Pilot Program Evaluation. The Cadmus Group, Sept. 2012, ma-eeac.org/wordpress/wp-content/uploads/Wi-Fi-Programmable-Controllable-Thermostat-Pilot-Program-Evaluation_Part-of-the-Massachusetts-2011-Residential-Retrofit-Low-Income-Program-Area-Study.pdf.
  2. ^ a b Huppi, Brian (19 Nov 2010). "System and method for integrating sensors in thermostats".
  3. ^ Environmental Protection Agency. Summary of Research Findings From the Programmable Thermostat Market. Washington, DC: Office of Headquarters, 2004
  4. ^ H Sachs. Programmable Thermostats. ACEEE, 2004
  5. ^ a b c "Manual vs Programmable vs Smart Thermostats | Which Is Best for You?". Service Champions. 2018-05-18. Retrieved 2018-12-06.
  6. ^ "The Honeywell Temperature Regulator".
  7. ^ a b c d Meier, Alan (2010). "How People Actually Use Thermostats". ACEEE. cite journal: Cite journal requires |journal= (help)[permanent dead link]
  8. ^ a b c d Lopes, Joseph. "FPL Residential Thermostat Load Control Pilot Project Evaluation" (PDF). ACEEE. cite journal: Cite journal requires |journal= (help)
  9. ^ a b "EIA's residential energy survey now includes estimates for more than 20 new end uses - Today in Energy - U.S. Energy Information Administration (EIA)". www.eia.gov. Retrieved 2018-12-07.
  10. ^ "About ecobee | ecobee | Smart Home Technology". www.ecobee.com. Retrieved 2018-12-06.
  11. ^ "The 50 Best Inventions of 2009 - TIME". Time. 2009-11-12. ISSN 0040-781X. Retrieved 2018-12-06.
  12. ^ "Nest Labs Introduces World's First Learning Thermostat". Nest. 25 Oct 2011.
  13. ^ a b Nest. "Support". Nest. Retrieved 2018-12-07.
  14. ^ a b Lu, Jiakang; Sookoor, Tamim; Srinivasan, Vijay; Gao, Ge; Holben, Brian; Stankovic, John; Field, Eric; Whitehouse, Kamin (2010). "The smart thermostat". Proceedings of the 8th ACM Conference on Embedded Networked Sensor Systems - Sen Sys '10. p. 211. doi:10.1145/1869983.1870005. ISBN 978-1-4503-0344-6. S2CID 207183167.
  15. ^ a b Hernandez, Grant; Arias, Orlando; Buentello, Daniel; Jin, Yier (2014). "Smart Nest Thermostat A Smart Spy in Your Home" (PDF). Blackhat. S2CID 14493263.
  16. ^ "Should You Get a Thermostat with Geofencing Technology?". General Heating & Air Conditioning. 2014-07-21. Retrieved 2018-12-07.
  17. ^ "Does the ecobee4 also have a built-in motion sensor?". ecobee Support. Retrieved 2018-09-21.
  18. ^ Whitney, Lance (February 12, 2014), "Google closes $3.2 billion purchase of Nest", CNET
  19. ^ a b c "Saving money with ecobee smart Wi-Fi thermostats | ecobee | Smart Home Technology". www.ecobee.com. Retrieved 2018-12-07.
  20. ^ a b c d e f g h i j "Energy Savings from the Nest Learning Thermostat: Energy Bill Analysis Results". Nest Labs, Inc., Feb. 2015, nest.com/-downloads/press/documents/energy-savings-white-paper.pdf.
  21. ^ a b c d e Asrish, Carlyn. Evaluation of the 2013–2014 Programmable and Smart Thermostat Program . The Cadmus Group, 9 Jan. 2015, www.cadmusgroup.com/wp-content/uploads/2015/06/Cadmus_Vectren_Nest_Report_Jan2015.pdf?submissionGuid=c8eda45b-2759-4a31-90e3-d2ecdb9001de.
  22. ^ Lee, Zachary (2022). "Unintended consequences of smart thermostats in the transition to electrified heating". Applied Energy. 322: 119384. doi:10.1016/j.apenergy.2022.119384. S2CID 249809288.
  23. ^ Tilley, Aaron. "How Hackers Could Use A Nest Thermostat As An Entry Point Into Your Home". Forbes. Retrieved 2018-12-07.
  24. ^ "Energy Use in Homes - Energy Explained, Your Guide To Understanding Energy - Energy Information Administration". www.eia.gov. Retrieved 2018-12-07.
  25. ^ "The Paris Agreement | UNFCCC". unfccc.int. Retrieved 2018-12-07.
  26. ^ "Social Impact | ecobee | Smart Home Technology". www.ecobee.com. Retrieved 2018-12-07.
  27. ^ "CNW | ecobee donates over 700 thermostats to Toronto Community Housing to improve sustainability and resident comfort". www.newswire.ca. Retrieved 2018-12-07.
  28. ^ "Smart Thermostat Incentives | San Diego Gas & Electric". www.sdge.com. Retrieved 2018-12-10.
  29. ^ "Smart Thermostats | Focus on Energy". www.focusonenergy.com. Retrieved 2018-12-10.
  30. ^ "Power Partner Thermostats". savings.austinenergy.com. 2013-04-24. Retrieved 2018-12-10.
  31. ^ "Smart thermostat rebate". www.pge.com. Retrieved 2021-09-29.
  32. ^ "Energy management for property managers". www.pge.com. Retrieved 2021-09-29.
  33. ^ "Smart Thermostat Rebate Program | The City of Naperville". www.naperville.il.us. Retrieved 2018-12-10.
  34. ^ "Energy Efficiency Programs | Entergy Mississippi, Inc". www.entergy-mississippi.com. Retrieved 2018-12-10.
  35. ^ Nest. "Support". Nest. Retrieved 2018-12-10.

Frequently Asked Questions

HEPA filters in AC systems typically need to be replaced every 6 to 12 months, depending on the systems usage and the manufacturers recommendations.
Signs include reduced airflow, unusual noises from the unit, increased dust or allergens indoors, and higher energy bills due to decreased efficiency.
Many HEPA filters can be replaced by homeowners following the manufacturers instructions. However, if youre unsure or uncomfortable doing it yourself, its best to hire a professional.
Yes, there are different sizes and specifications of HEPA filters designed to fit specific AC models. Its essential to use the correct type for your system for optimal performance.
Failing to replace a HEPA filter regularly can lead to poor air quality, reduced system efficiency, potential damage to HVAC components, and increased energy consumption.