Seasons in a Passive House

Illustrations by Michael Eddenden

Winter

It’s a bitter morning. I’m admiring the icy frost on the exterior windowpane. A cup of tea in one hand, tracing the delicate patterns with the other, I feel toasty warm sitting—I might as well admit, in the cat’s window nook. It’s a tug-of war. I can sit here only if I move Angus first, usually several times. It’s comforting to know the kitchen’s warmth does not leak through the triple-glazed windows as proven by the frost buildup. In my old house the walls were too shallow for a window seat and there was condensation and fogged glass on the window.

Having a completely silent home has made my new routine a joy to perform. I have taken up yoga for my New Year’s resolution and the absence of a furnace constantly turning on and off means my space remains peaceful. Putting my hand against one of the air grills, I feel a soft puff of air. I remember when I would have drowsy bouts late in the day in winter, cocooned at home. Yet these past few months, although I have stayed indoors, I feel refreshed from the constant fresh air in every room. No stuffiness. No stale air. I feel as though I’m getting healthier—more oxygen, with every breath.

The dry winter months play havoc with my appearance; from fly-away hair to scaly skin. Breathing dehydrated air also increases my vulnerability to asthma, bronchitis, sinusitis, and embarrassingly, to nosebleeds. It was frustration with all this—with modern homes dependence on machinery, furnaces and air-conditioners, that coerced me into considering a Passive House. Like other North American architects I was vague on the science; it was an eco-buzzword floating around the office. European. Now we, Kearns Mancini, are experts, proselytizing the concept, and the building code is set to adopt the principles.

It was the energy recovery unit, the regrettably named ‘ERV’, that solved my air quality problem. In winter, heat and humidity is transferred from the warm and moist air inside to the supply air—the cold, dry air coming from outside. In the summer the reverse happens: heat and moisture from the air outside is transferred to the exhaust air stream, leaving supply air coming into the house that is cool and fresh but without the humidity.

Last week we had a power outage. Three days of high winds meant the power grid could not be fixed. This was the ideal test of the super-insulated walls. Outside the temperature plummeted, dropping below -18˚C, and all I thought was: how cozy, how airtight, the house felt.

Spring

Daffodils signal spring. Rain too. Next will be the leaf buds forming on the maple and cherry branches. Just outside the west facing windows, the deciduous trees we planted will form a canopy shading the setting summer sun and blocking the afternoon heat before it passes through the triple pane windows. It will cast the perfect light for writing. By orienting the building with the sun’s travel, planting trees as natural shading devices, and keeping the building design compact, our home is the embodiment of what I deem Intelligent Architecture.

The season of growth brings the excitement (work) of gardening. I have taken advantage of the two-foot thick walls (R-60 insulation) to place my seedling trays in the deep window nook. It’s generous. There’s room enough to accommodate my potted plants: herbs and flowers.

These can be the cruelest months too. Seasonal allergies keep me indoors on days with high pollen counts, days spent avoiding the outdoors—especially in this house. There are HEPA filters in the ERV unit. They clean the incoming air far more thoroughly than the filters in the other houses I have lived in, those that had filters. This house is a relief. My symptoms are mild, I require less medication, and I sleep better. The ERV purifies the “lungs” of my home.

My unit was designed with an open loft above which I have adopted as my home office. I was concerned that it would be hot and stuffy; warm air rises. However, the ‘vertical temperature gradation,’ as the technical minded term it, was minimal. Due to the constant flow of air the loft remained…pleasant. Any heat build-up generated by multiple computers was dissipated with the constant movement of air. It wasn’t just an office, but a retreat. So much so, my son added his desk. I’ve often found we work together now. His interruptions with the latest Reddit trivia can be trying but I get to see what homework he does.

One of my spring-cleaning tasks is window washing. In addition to the benefits of the window’s high thermal performance, their tilt-and-turn operation provided easy access for a thorough clean. The windows open inwards so they can be cleaned from inside. The window’s tilt position is ideal for ventilation. And borrowing the fragrance of the blossoms.

Summer

It was July of 2019, when my husband and I moved into our six unit passive house building. Our decision to choose a Passive House was three fold:

1. To be our final house, if possible. Long term ownership. A robust home built to “Age in Place”. I intend (hope?) to pass this home to one of my children.
2. Health benefits of an oxygen-rich, constant clean air supply.
3. Our decision to live lightly – reduce greenhouse gases.

Summer is unfortunately the season of road construction and my neighbourhood was one of the slated projects this year. However, closing the windows vastly reduced the noise. The acoustic performance of the triple-glazed windows even blocked out the raucous kids at the adjacent pool party. And the cannabis smoke, although that wasn’t due to the windows. Following our week vacation in August, we returned home to a pleasant surprise. I had expected the typical musty smell after our old house had been sitting empty and shut down for a week. Our home was exactly as we had left it, a clean fresh scent. No trace of the smoke. The ERV has an option to set on Holiday mode, with minimal air circulation.

It also works well in Party mode. When we arrange our potluck get-togethers, we let the cool morning air blow through before closing the windows and set ‘ERV’ to Party mode (High). Without air-conditioning we were cool. A meter monitors the CO2 level. When, as more people show up, the CO2 level rises, ‘ERV’ ramps up circulation.

Generous overhangs above the windows block the intense summer sun when it is high in the sky, but without a loss of natural light. Daylight remains abundant. All the living spaces face south and fill with it. During these long summer days we use fewer lights now, and they aren’t on as long, saving money. And cooling the house. Grouping the habitable rooms along the south face also benefits ventilation. The living room and bedrooms are supplied with fresh air 24 hours a day while stale air is exhausted from the service rooms, the bathrooms, laundry and kitchen. It’s just being practical.

Fall

During harvest, I’m more adventurous with my cooking. I want to try new recipes and sample foods from different cultures. Perhaps fortunately, with the constant ventilation, even smells of stir fries and curries are quickly eliminated. A kitchen in a Passive House doesn’t even require a standard exhaust hood above the stovetop, as the room’s exhaust vent is sufficient to dissipate the steam and odors. Continual air movement has other unlooked for advantages. I sometimes design our meals around the efficiency of the home’s temperature balance. On cooler days I put a roast lamb or stuffed squash in the oven, or use the slow cooker because they generate heat.

In October the temperature dropped, but we were able to use all the rooms as they were meant to be used. Angus kept to his favourite spot curled up on the window seat. Claiming his space. Napping on and off in the sun, he watched the birds. Even though the windows open they are airtight when shut. Even the patio doors are free of drafts. There was absolutely no thermal bridge along the edges of the still warm concrete floor.

Preparing for the upcoming winter in the past involved a yearly furnace maintenance: inspect heat exchanger, clean pilot, check gas line and shut-off valve, check fan switch, and so on. With a Passive House ERV, the only maintenance needed was replacing the HEPA filters. In my previous house, Fall meant cleaning the numerous air vents installed in the floors, walls and ceilings, an unnecessary chore in a Passive House.

November’s Utility bill arrived—I was thrilled! A 90% reduction! Because our South facade has 30% window area, 60% of the home’s heating comes from the southern sun. The low-angled winter sun adds heat to the inside, and the thick walls let barely any of it escape. It was a reminder how easily it would be to take all this for granted: one only notices how comfortable a home is by absence of that comfort, too cold or too warm, and drafty. I could say the same about other aspects of Passive House life, such as the missing odours, or the lack of noise, whether from outside or from the mechanical drone of machinery inside I’d always accepted as unavoidable in other homes I have lived in.