Passive House Principles
Super-Insulated Building Envelope
Continuous insulation around the entire building reduces energy demands and increases comfort. Because of the increased ability to retain heat through the building envelope (or block it in warm weather), the size of the heating/cooling system is significantly simplified and reduced.
For single-family residential homes in the Hudson Valley (climate zones 4a, 5a, and 6a), triple-pane windows are usually necessary. In addition to better insulated glass, Passive House-approved windows reduce drafts through improved air-tightness when they are pulled closed.
Airtight Building Envelope
The building envelope is extremely airtight, preventing infiltration of outside air and loss of conditioned air. A small change in the air- tightness of a building makes a big difference and it’s accounted for from the beginning of a project. While the current building code already requires air-tightness verification, the Passive House standard is far more stringent.
Most homes do not have a system for delivering fresh air for healthy living. We have relied on air leaks at gaps that allow outdoor air to move in or out, such as leaky windows and doors, recessed lights and other openings, and where the house meets the foundation. These unintentional gaps also allow moisture movement, are a pathway for bugs and rodents, and introduce dust. Passive buildings use heat recovery ventilation systems (HRV), or, more commonly, energy recovery ventilation (ERV). In an ERV, exhaust air is replaced with outside air, but the heat and moisture of the air leaving the building pre-conditions the incoming air. The result is fresh indoor air with only minimal energy penalty. Incoming air is filtered, so if
the windows stay closed the home will be surprisingly dust-free.
Benefits of Passive House Construction
Long-Term Cost Savings
Even as building energy codes require higher insulation levels and greater air-tightness, the Passive House standard provides a 40 percent to 90 percent reduction in energy consumption when compared to a code-built home.
Reduced Carbon Emissions
Less energy use translates directly to less carbon emitted into the earth’s atmosphere. According to the AIA Architecture 2030 plan, the building sector accounts for roughly 40 percent of our total global carbon emissions.
In the old way of building, we created a leaky building envelope and then oversized our heating equipment. When the building envelope is sealed and super-insulated, the movement of water vapor can no longer have a direct avenue to dry out and can no longer cause serious durability issues.
Improved Thermal Comfort
Thermal comfort is determined by the surface temperature of a surface. If it is within seven degrees of the living area, most people will find that to be very comfortable. Every interior surface in a Passive House is verified to fall within this comfort criteria.
Superior Indoor Air Quality
A requirement for Passive House certification is a balanced ventilation system. These systems, known as HRVs or ERVs (heat/energy recovery ventilators) bring fresh air in from the outside, move it throughout the house, and then expel the stale air to the outside. In the process, the air is filtered with a MERV 13 filter (minimum requirement) which has proven to drastically reduce allergens and other particulates from the air we breathe.
The Path to Net Zero
A prerequisite for Passive House certification is the Department of Energy’s Zero Energy Ready Home program. Whether renewable energy is immediately installed on the project or not, it is engineered for the smallest energy demand possible so that net-zero energy consumption can easily be achieved.
NYSERDA Building Better Homes Initiative
In partnership with the New York State Home Builders Association and the Asthma and Allergy Foundation of America, NYSERDA has established the Building Better Homes: Emissions Free and Healthier Communities program. This first of its kind program will partner with home builders and developers to advance carbon-neutral home and neighborhood development across the state. The initiative is part of an over $30 million multi-year investment to decarbonize single family home new construction. Homebuilders can apply for funding up to $250,000 to decarbonize their building practices to build high-quality, reliable, and sustainable carbon- neutral homes. Later this year, NYSERDA will launch a program educating homebuyers on healthy and emissions-free home construction.
Passive House Alliance–Hudson Valley
Passive House Alliance–Hudson Valley is the local chapter of the nonprofit Passive House Alliance US in the Northeast. It provides a robust membership-based network with members throughout North America and provides training, resources, marketing, and advocacy support to its members throughout New York, New Jersey, Connecticut, Pennsylvania, and New England. Its mission is to contribute to a low-carbon future through education, training, and advocacy for the Passive House standard and make it the mainstream standard of building in the Hudson Valley and beyond. Local Hudson Valley Passive House-certified consultants, builders, and verifiers can be located on its website: Pha-hv.org.