Because the poor air quality of standard buildings creates a significant risk to health, zero energy homes and buildings have several health-related advantages over conventional buildings. Most conventional buildings and homes are constructed without much consideration for air quality and health issues. Many builders simply rely on compliance with standard building code. The requirements for building to zero, on the other hand, include delivering healthy indoor air quality. Zero energy builders understand healthy indoor air quality (IAQ) and how best to deliver it.
The result is that zero energy homes and buildings embrace design and construction techniques that provide superior health, functioning, and well being through improved indoor air quality. Here we explore the building strategies needed to make these benefits a reality in newly constructed zero energy buildings. In Part Three, we will explore steps that can be taken to improve the indoor air quality of existing buildings.
How New Zero Energy Buildings Optimize Indoor Air Quality
Zero energy and zero energy ready homes and buildings, which are constructed according to the EPA’s Indoor Air Quality Plus program, are designed to provide exceptional indoor air quality from the very beginning using three strategies. The first is the exclusion of outside pollutants and toxic building materials and finishes. The second strategy involves installing a comprehensive ventilation or fresh air system to expel or dilute pollutants. In the third, filtration captures airborne contaminants that escape the first two strategies.
To achieve exclusion, a zero energy building is constructed to be highly air tight, with less than two air changes per hour, excluding outdoor air pollutants. The home is also built with green materials and finishes that do not contain formaldehyde, VOCs, or other off-gassing chemicals. The most exacting zero energy homes avoid the “Red List” of toxic materials found in common building materials. And, since zero energy homes produce their own electricity from solar panels, they can be all electric homes without gas stoves, gas furnaces, or gas water heaters. As a result, they do not pollute the indoor air with harmful CO2, NO2, CO, formaldehyde and ultra fine particles resulting from gas combustion in the building. Most zero energy homes and buildings are also built to control moisture, so that they do not develop decay or mold problems that can also contaminate the indoor air.
Because they are designed to be very airtight to exclude outside pollutants, zero energy homes and buildings must avoid trapping indoor sourced air pollutants and moisture. As a result these homes are designed with a robust, balanced fresh air ventilation system. Either a ducted heat recovery ventilation (HRV) or energy recovery ventilation (ERV) system is most commonly used, although a lower-cost spot ERV, such as the Panasonic WhisperComfort ERV, may be more cost effective in some situations. All these energy efficient fresh air systems exhaust “bad,” stale air, filter incoming fresh air, distribute the filtered fresh air throughout the home, and dilute any remaining or newly generated indoor pollutants. HRVs and ERVs also retain the temperature in the home and, in most circumstances, these ventilation systems maintain an acceptable level of indoor humidity.
One important function of ventilation is to maintain the proper moisture balance. Indoor relative humidity that is either high or low can be problematic. For health purposes, relative humidity (RH) between 40% and 60% is generally considered best. Since much indoor humidity is generated by sources inside the home, such as cooking, washing, and breathing, it is also used as a yardstick for measuring adequate ventilation. Every home should have a simple humidity meter, i.e., hygrometer, to measure RH, so that occupants can learn to properly operate the ventilation system to maintain the desired humidity.
ERVs and HRVs come with their own built in MERV 8 filter that helps to filter the air and improve indoor air quality. In some areas excessive outdoor pollution can be a concern. This can take the form of extremely high levels of pollen, dust, smoke, aerosols, or other potentially toxic substances, which may not be fully removed by the standard system. In these cases, a HEPA or MERV 13 air filter could be added onto or integrated into the ventilation system or a stand alone HEPA air filter can be used to supplement the ventilation system.
The Health Benefits of Zero Homes and Buildings
These strategies taken together, ensure that zero energy and zero energy ready homes and buildings provide superior indoor air quality and health for their inhabitants.
As we demonstrated in Part One of this series, the health benefits of high IAQ, whether at home, work, or school include reduced illness (including cardiovascular disease, diabetes, lung conditions, and cancer), improved sleep, improved cognition, and improved productivity. They also include fewer asthma related emergency room visits, and improved health. Additionally, steady, comfortable indoor temperatures result in fewer cold and heat-related deaths, less hypertension, heart disease, asthma, and Chronic Obstructive Pulmonary Disease (COPD). A fresh air system in an airtight zero energy home or building is like an invisible “shield” that helps prevent colds, flu, asthma and allergies and improves cognition and productivity.
How Zero Buildings Benefit Everyone
Zero buildings not only increase the health, functioning, and well being of their inhabitants, they benefit society as whole because they foster higher productivity, improve cognitive functioning of workers and students, and lower the rather significant expenditures on pollution-related illnesses and associated emergency room visits that tax our healthcare system. There is another significant, but under appreciated, benefit of zero energy buildings to society. Zero energy buildings improve the quality of outdoor air as well because they use no fossil fuels and emit no pollutants. With additional solar collectors, buildings can produce more energy than they use and can even power electric vehicles from the sun, further reducing outdoor air pollution. Zero buildings are a win all around.
The Future is Zero
The quality of air we breath indoors and out is a major factor in our health, quality of life, and effective functioning. At the same time global warming, reduced regulation, increased use of synthetic chemicals, and population growth are exacerbating pollution. As a result, we all need to help create a future where we can breathe fresh air with close to zero pollutants – indoors and outdoors. Zero energy homes and buildings will be a big part of the solution. It’s a solution with positive side effects: reduced energy bills, greater comfort and reduced carbon emissions. For all these reasons, zero energy homes and buildings and zero carbon electric transportation will be part of the future we can create. The good news is, zero energy homes and buildings and electric vehicles are in production and available for us to choose right now. What are we waiting for? Let’s go for it!
Original Story by: Zero Energy Project