Ventilation for Designing Better Buildings

Passive House: Is It Worth the Cost?

Posted by Sarah Lozanova

Mar 1, 2017 3:26:23 PM

 

When building a home, the material selection and design impact the energy bills, durability, and indoor air quality for decades. Going beyond code requirements in home insulation, air sealing, and heat recovery ventilation saves energy and boosts occupant comfort. These features also increase the project’s cost. Although there are many advantages to building to the Passive House standard, is it worth the additional upfront cost?

What is the Passive House standard?

Passive House is a rigorous international building standard for energy efficiency in buildings and includes criteria for energy demand and airtightness. Passive House–certified projects are up to 90 percent more efficient to heat than a project built to satisfy the minimum code requirements. Passive House–certified components, including windows and heat recovery ventilation systems, help builders and designers meet the Passive House standard.

Certified Passive House buildings now account for 2 million square feet of building space in North America, representing a threefold increase over 2015. Several jurisdictions have policies that support Passive House and other high-performance construction methods, and a growing body of professionals have been trained in Passive House design and construction. Those are findings in a recent study by the Pembina Institute about the increase in high-performance building enclosures and the Passive House movement.

Is there an additional cost?

Because Passive House construction typically requires triple-pane windows, generous amounts of insulation, and heat recovery ventilation, there is often an increased cost associated with constructing the home. Keep in mind that building codes vary by location, so it is difficult to anticipate the price premium. Also consider that the load requirements for the heating and cooling system are greatly reduced or possibly eliminated, cutting some costs.

For example, Belfast Cohousing & Ecovillage in Midcoast Maine features 36 units built to the Passive House standard. Despite its location in a cold climate, the homes feature a modest electric baseboard heating system and Zehnder heat recovery ventilation system. Most new homes in the area require a far more extensive heating system yet contain less expensive insulation, windows, and doors. Alan Gibson, a principal of GO Logic, the firm that designed and constructed the homes, estimates that making these homes satisfy the Passive House standard added 7% to the cost.

There are, however, examples of homes built to the Passive House standard that don’t have a higher upfront cost, such as this home in Ireland. Although the upfront construction cost may be higher, the heating and cooling costs are 40%–90% less, resulting in decades of cost savings.

How do we quantify the benefits of Passive House?

Although the energy costs associated with a Passive House are significantly lower, many of the other benefits are harder to quantify. Heat recovery and energy recovery ventilation systems promote indoor air quality by continuously supplying fresh, filtered air to the living spaces while exhausting stale, contaminated air from the bathrooms and kitchen. Heat is transferred from the exhaust air to the intake air, lowering energy bills.

By contrast, most conventional homes rely on gaps and cracks for ventilation, but heat isn’t captured before the air leaks out of the home, and it is difficult to control the quality of the incoming air. For example, contaminants can enter the home through an attached garage or from a musty basement.

“Indoor air quality is an important part of the equation [when deciding to build to the Passive House standard],” says John Rockwell, a technical sales engineer for Zehnder America. “If a family has a child with respiratory issues, of course, it is worth it.”

Zehnder heat recovery ventilation systems are Passive House certified and have filters that can remove pollen, dust mites, mold spores, and even bacteria. The systems also remove excess humidity, which can prevent mold growth.

Homes built to the Passive House standard typically don’t contain natural gas furnaces and propane ranges because of the impact of fuel combustion on indoor air quality. Passive House dwellings are also more comfortable because air sealing prevents drafts, and generous amounts of insulation ensure even temperatures throughout the dwelling.

originally posted here

Topics: Passive House