Ottawa Construction News staff writer
Passive House (PH) consultants and experts Gunter Lang and Andrew Peel offered their perspectives about the sustainable and extremely energy-efficient building standard at a March 12 event co-ordinated by the Construction Specifications Canada (CSC) Ottawa chapter.
More than 130 City of Ottawa employees and social housing providers, architects, engineers and consultants gathered in a Beaver Barracks conference room on Metcalfe St. for the morning session. The 254-unit mixed affordable rental housing project, developed and managed by Centretown Citizens Ottawa Corporation (CCOC) provided an appropriate setting, because of the project’s own adherence to sustainability objectives.
Guests and participants learned about Salus Clementine, an environmentally-sustainable $7.5 million, 42-unit project to provide housing for individuals living with mental illnesses which will begin construction this spring.
Austrian-based Lang is a PH movement pioneer and leader. Several major projects have been completed in Austria, Germany, Belgium and other European countries with energy efficiency and comfort standards that have raised the bar for cost savings, without significantly increasing construction costs.
Lang said European standards have reached the stage that, by the year 2020, all new buildings must be nearly zero energy, and retrofits must achieve nearly equivalent savings.
While North American builders are reaching higher standards with the Energy Star program with overall 42 kWh per sq. m. energy demand, Passive House requires the demand to be kept to 15 km. per sq. m. “In the U.S., less than .06 of projects are built to meet that standard,” he said. “Austria has 25 per cent built to that standard.”
When Passive House standards are implemented, he says you can heat an entire house with a hair dryer.
The key to the system’s success, largely, is extensive insulation, an airtight building envelope, extremely efficient window systems, avoidance of thermal bridging, and a ventilation system that keeps the air fresh and the building comfortable. For example, wall, roof, and floor assemblies often exceed R50 performance, while windows may require U-values less than 0.13 Btu/(h ft² F)
Lang’s own house in Austria requires only 1,060 kWh a year for heating, hot water and cooling, equivalent to only 11 liters of alcohol. “I need less energy to heat the house than I drink at the same time,” he said.
While there are still challenges in sourcing North America PH building products, in Europe “today there are more than 300 companies that have certified Passive House windows.” These highly-efficient windows may cost a bit more than conventional windows, but the operating savings are sufficient to generate almost immediate operating payback, especially when the costs are amortized in mortgages, where the slight increase in monthly financing costs is far more than offset by reductions in energy bills.
Lang described several large-scale European PH projects including public buildings, schools, prisons, hospitals and office towers.
In one case, he said, a 279,000 sq. ft. multifamily building with 354 apartments uses the equivalent energy consumption of an 8,690 sq. ft. property – “the same as six single family houses.”
European building costs, meanwhile, are comparable to regular construction, ranging from $118 to $202 per sq. ft. “Most of these prices are not more than your conventional buildings in Canada,” he said.
Meanwhile, Andrew Peel, the first Canadian accredited PH certifier, described some of the opportunities and challenges in applying the building standard in North America.
“One of the most important parts of a Passive House, is the requirement for high-performance ventilation systems,” he said.
In contrast to conventional systems, which focus on heating or cooling the air, the primary role of PH ventilation systems is ensuring a continuous renewal of the indoor air, while avoiding mould, pollutants, carbon monoxide build-up, and unpleasant odors.
This is achieved through proper design, installation and commissioning. The systems require “high performance components, that do what the manufacturer tells us they do,” Peel said. There’s also a need for occupant education and periodic maintenance.
PH projects require ventilation supply vents to be included in all living spaces, and extract vents in all “wet rooms” such as kitchens, bathrooms, and washrooms.
The systems are designed to refresh an entire house’s fresh air every two to three hours.
Peel says meeting the PH standard require high performance HRVs (Heat Recovery Ventilators) or ERVs (Energy Recovery Ventilators), which are more difficult to source in North America.
While these cost more than conventional ventilation systems, and the added insulation and higher-quality window systems also are more expensive than conventional construction, PH projects do not need furnaces or other expensive mechanical systems, saving money on that aspect of the infrastructure.
There are still challenges in sourcing products and completing commissioning. In one case, Peel said he could not certify a project because, despite the efforts of the builder/owner, the selected HRV unit didn’t meet the PH’s performance requirements.
In an interview, Peel said his GTA-based consultancy has been growing rapidly as more people adopt PH design and construction principles and seek certification to verify their designs.