Passive House: What is it Really?
by Nancy Greenwald
Have you heard of passive house? The idea is gaining in popularity, and for good reason. It’s time for all of us to learn about passive house.
So what is it? Passive house is a term used to describe a unique approach to energy efficiency that creates sustainable and resilient buildings. The central concept is the active utilization of existing energy. A building constructed employing passive house principles uses passive heat sources — the energy of the sun, heat from running household appliances and from extracted air — to satisfy most of the heating demand. Remaining energy needs are supplied by renewable energy resources like solar panels and heat pumps. The idea is to optimize thermal gain and, at the same time, minimize thermal losses.
The principles of passive house are not limited to homes, as the term might suggest. The principles can be applied to multifamily housing. They can be applied to office buildings, even to skyscrapers. It’s also possible to retrofit buildings to conform to passive house standards. Standards in this country are set by the Passive House Institute U.S., which provides certification for both buildings and products. Passive house standards are voluntary.
Passive house is based on five essential principles:
- A high level of insulation.
- Airtight windows and doors.
- A mechanical ventilation system with heat recovery and heat efficiency.
- An orientation designed to make use of passive solar gains.
- No “thermal bridges” (a “thermal bridge” allows heat to be lost through poorly insulated parts of a wall).
Other characteristics of passive house construction include low-energy appliances and energy-efficient lights.
What are the savings? According to Green American Magazine, meeting passive house standards cuts down the energy used to heat a home or other building by about 90% and reduces the total energy use by at least 60% to 70%, while providing superior indoor-air quality.[i] Space heating, space cooling, and water heating are some of the largest energy expenses in any building, so these savings are significant over time.
What does it cost? Employing passive house principles is an investment in long-term savings. While the initial costs of construction are currently higher (estimates range from 5% to 15% higher), this initial investment is offset by decades of savings in energy costs.
What does this mean for multifamily homes in Connecticut? All multifamily housing financed through the Connecticut Housing Finance Authority (CHFA), including tax credit allocations, must comply with the Multifamily Design, Construction and Sustainability Standards and Guidelines, resulting in housing that’s as energy-efficient, cost-effective, and sustainable as possible. CHFA supports the use of passive house.
Ready to learn more? On May 14, the Construction Institute will delve into the details, with an experienced panel discussing passive house design considerations and the CHFA process. Their case study is the multifamily and townhouse development at 11 Crown Street in Meriden, Conn. The program is part of the Construction Institute’s “101” series, which is designed to bring together experienced practitioners and those new to a concept to dive into a particular facet of the industry. Learn more on our website: construction.org.
[i] “Passive House, Aggressive Savings,” available at https://greenamerica.org/efficiency-first/passive-house-aggressive-savings
Nancy Greenwald
Nancy Greenwald is the executive director of the Construction Institute.
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