The sub-title for this post really should be “how comfortable is a passive house in winter?” And the answer is: very!
Okay, so the sun has been shining and we’re feeling the summer’s warmth, but cast your mind back to the long, grey winter we had here in the Ottawa Valley. Not for long, just long enough to picture the environment in which the EkoModel passive house spent its first winter.
Although the average temperature for the area was roughly -5.5C from December through March, December and January both saw some supremely cold days: -28C the low in December, -25C the low in January. Throughout the period we kept the house at steady 21C for daytime and evening; overnight, with no heating, the temperature would make a gentle fall to 18 or 19C by morning.
Having lived in homes in the past where keeping the temperature at 21C would have been too costly, this round the clock comfort was the revelation we hoped it would be. Both floors of the home, including the upstairs bedrooms, maintained these temperatures – no ‘cool spots’ as in many older homes.
All of this was achieved using an average of just 31.75 kWh per day – which may not seem that low, until you remember that this passive house has NO FURNACE. That hydro-electricity usage simply represents the operation of the ‘solar engine’ components (including a fresh air exchanger, and an air-to-air heating and cooling pump) of the house, and daily living (lights, cooking, heating water*, PC and television usage) of a family of five.
So, our total energy bills for the four deep winter months was $801.48 (or $200/month).
*We heat our water to 120C.
An interesting note on Sunny Days
If it was a sunny day and we had approximately six hours of sun or more pouring through the south facing windows, we did not need to use the heating system at all.
The sun had no problem raising the temperature of the house from 19°C in the morning to about 24°C in the afternoon, in which case the temperature would drop to about 22°C in the evening and hover at about 20°C in the morning. Amazing!
What we’ll do differently next year
Overall, the house performed as expected, and the very low energy usage (seen here) and bills, even in a cold, grey winter, are great practical evidence. Less easy to share, but no less significant, is the supreme comfort that we enjoyed all winter long.
Looking ahead to next year, we’re considering installing an ethanol (biofuel) fireplace. These units are a very simple and clean alternative to wood burning fireplaces and woodstoves, and their benefits are amplified in a passive house, where much less heat input is required to warm the home, and a fresh oxygen supply with good airflow is continually available.
There is a great overview of ethanol fireplaces on Houzz, and again we’d underscore the greater benefit to a passive house over a conventional build. In brief, this heating method has a very small environmental footprint, is low maintenance and attractive. We see this heat source as a great alternative when sunshine is severely limited, as it was this past winter in the Ottawa Valley. Any successful system has a built-in backup, and this looks like a great way to round out the solar engine that is driving our passive house.
Questions about the passive house performance?
If you have questions or thoughts about our passive home’s winter performance, please do feel free to comment here or contact us. We’re keen to share this information as clearly as possible in order to help homeowners to understand the huge benefits of building a passive house.