Passive Architecture Delivers on Comfort, Durability and Efficiency

• Originally published in the June 2017 edition of Lydia's Style Magazine.

Imagine a home where overhead lighting isn’t needed during the day because of how the windows are configured. Imagine a house insulated from the sounds of traffic and car alarms, where the temperature stays within a comfortable range year round.

Passive architecture can deliver all those things.

In West Fort Collins, the night wind coming off the foothills can sound like a banshee, but not for Jim Donohoe.  Sounds of motorcycles, dogs barking and stereos go unnoticed within his passive house.

“The quietness of the house is really amazing," he states. "That’s one of the big advantages of the 2-foot thick walls and the triple pane windows.”

Passive House Consultant Andrew Michler argues that passive architecture can achieve greater energy savings than more sophisticated and costly upgrades like solar panels.

“You put your money into the envelope of the house and the design of the house. Then you actually provide a much better space to live in as well as something that is much more efficient.”

A software engineer who works from home, Donohoe rides out dramatic temperature fluctuations in comfort unaided by a furnace or air conditioner. The home has five electric baseboard heaters which he reckons kick on twenty or fewer days a year.

“This house that I’m in now, it’s just naturally very easy to stay in a much more comfortable temperature range because it just doesn’t get all that cold in the winter," he says. "And in the summertime it generally doesn’t get that hot."

Materials and layout of a building’s exterior are fundamental to passive architecture. A building’s envelope—foundation, outer walls, doors, windows, ceiling and roof—dictates how much it will rely on artificial heating, cooling and lighting.

Michler, author of the book [ours] Hyperlocalization of Architecture, designed and built the first certified International Passive House in Colorado. He’s lived off the grid for two decades, relying largely on passive design principles.

The Passivehaus Institute in Germany developed the Passive House certification, which was widely adopted in Central Europe.  More recently, the Passive House Institute US (PHIUS) created its own certification.  Recognizing that climates vary greatly in North America, the criteria are performance-based rather than prescriptive.  PHIUS buildings must use 86% less energy for heating and 46% less energy for cooling than others in their location.  It’s the opposite of a cookie cutter approach.

Of course, a home doesn’t need to conform to the certification to benefit from these techniques. Still, the idea of living in a Passive House is enticing.

Ceiling fans are enough to keep Donohoe’s home cool in July. By leaving his windows open at night and closing them in the morning, he traps cool air in during the day. The home's structure keeps the elements at bay with little help from man or machine.

Passive House is an extension of the passive solar techniques popularized in the wake of the 1973 energy crisis, and passive solar principles remain relevant. That’s particularly true here in Colorado’s Front Range due to the abundant sunshine.

“Colorado actually is one of the prime places on the planet for Passive House to work very effectively at a reasonable price and effort," Michler states. That’s because the geophysics of Passive House works especially well compared to conventional design under cold, sunny conditions.  Good passive architecture, however, performs well year-round.

Architect Brian A. Majeski has designed or been on a design team for three passive homes in Colorado, two of which were certified Passive House. The Principal at Urban/Rural Design in Fort Collins, he’s also a proponent of passive architecture. Among other aesthetic features, he admires the deep window and door openings in passive homes, a product of their thick walls.

“They’re deeper. The door openings are deeper. If you’re in a two-by-four home it feels like you’re in a paper box. It’s really thin, and if there’s a big storm outside it’s not very sheltering.”

Windows are “more like portals,” so innie or outie windows can be used. The former option allows windows to be set back from the home’s exterior, sheltering them from wind and direct sunlight. The latter option allows placement of potted plants and décor in the niche. It’s just one feature that conserves energy and looks good.

“Balancing of Objectives”

Some architectural features, such as dormer windows that project vertically from sloped roofs, become infeasible for someone trying to build a truly energy efficient home. The more angles in a home’s exterior, the more difficult and costly it becomes to control what’s called thermal bridging. That refers to heat transfer resulting in unwanted gains in the summer and losses in the winter. For that reason, Passive Houses tend to have somewhat boxy designs.

Passive architecture isn’t as central to Majeski’s brand and reputation as Michler’s. New homeowners, he points out, can work with architects to balance the objectives of efficiency, budget goals and their aesthetic ideals. There’s a lot of room in the middle of the field, and to Majeski it’s a values call.

Additional upfront costs depend on a person’s commitment to energy savings, but they aren’t prohibitive.  A more open floor plan will recoup some of the extra costs that go into a Passive House’s envelope. Building a high-efficiency home will also allow for a smaller HVAC system and less ducting than would otherwise be needed. So the up-front costs don’t quite even out, but they can be managed.

Architects agree that in a region with comparatively-cheap energy, passive architecture is more about comfort and environmental stewardship than saving money. Nonetheless, a 2,000 square foot Passive House will require $20 - $30 per month for utilities … in the dead of winter. Not bad.

Retrofitting Your Home

Sadly for some, this has nothing to do with 1980s pop culture. Retrofitting means modifying an existing structure to improve its performance. While the most important elements of passive architecture must be planned before the setting the foundation, there are still many ways to improve a conventional home’s efficiency without feats of engineering.

"Most people want to go straight for the windows or insulate the attic or something like that,” explains Michler. “Sometimes that’s the right thing to do, and sometimes that’s not the best solution with somebody with a limited budget."

Understanding how the orientation of a home influences thermal bridging, solar gain and interior light quality is key. It will help direct attention to the best opportunities and forego upgrades where they aren’t cost effective. “Solar gain” refers to how the sun heats a building through exterior walls and windows. Logically, these should be exposed during the winter and shaded during the summer. The sun’s position in the southern sky changes, so calculated overhangs and landscaping allow or block sunlight according to the season.

Triple-paned windows make the most sense in areas exposed to wind and direct sunlight. It might make sense to place awnings over windows on the southern side of a building if the roof or trees aren’t blocking out the summer sun. Louvered panels can be a visually-pleasing way to block solar glare and add privacy.  Adding vertical solar shade fabrics to a home’s west deck can likewise block out unwanted solar glare.

This is important. 

"A lot of people have West windows in Steamboat and they bake in March and late February,” notes Majeski. “It’s hot.”

Modeling software can help homeowners determine which types of windows and overhangs to use. That level of planning sophistication is not necessary, however, unless energy savings goals are really ambitious.

Finally, Energy Recovery Ventilators (ERVs) exchange stale air from the interior for fresh, filtered air from the outside. Many HVAC technicians can install ERVs, which most benefit people living in densely-populated or high-allergen settings. It can be unhealthy to live in a tightly-sealed home without an ERV due to indoor air pollution.

Questioned about the overall comfort of his home, Donohoe, who moved there from a conventional home two blocks away, is emphatic: “I think it’s much more comfortable.”

Passive architecture delivers more predictable energy savings and comfort than conventional homes, while preventing mold and other maintenance snafus. No matter how cost-competitive solar panels become, daylight, shading and solar heat will always be free.