How Low Can We Go?
Well, it's almost go time! Spring is pretty much here in Red Deer, and we've spent the winter planning, designing, modelling, re-modelling, material selecting, comparing mechanical equipment and re-modelling some more! After some consideration and after reviewing the output of both Hot2000 software and Passive House Planning Package (PHPP) software, we've determined that the Thomas House will not require as substantial modifications as we initially believed. At this point, we will be keeping all patio doors according to plans, and only reducing the size of one north-side window to reduce heat loss on that side. More on our windows further down. We've decided to rely solely on our wood stove as our source of heat throughout the year as our modelling shows that we will be sufficiently covered in the heat department due to the home's insulation values & air-tightness (if we do our job properly, that is). For additional heating during those -35 degree Celsius days, we will put small electric heaters in the basement when necessary.
We were lucky to get to this point through revisions and carefully planning certain details as the alternatives we were considering had substantial drawbacks. Our previous heat choices, the heat pump and the radiant floor/ceiling heat, were both costly (the equipment for the pump, and the installation for the radiant), while also increasing our energy load. This results in having to size our PV system much more than we cared to, since keeping a low-energy footprint was our primary goal. When our most recently modelling revisions became solidified, we removed these heating possibilities. I'll be honest, it made me a bit nervous to solely rely on the HRV, wood stove & portable radiant heaters, when most houses have full-on giant furnaces. Hopefully practice matches theory, but only time will tell with our first winter inside the Thomas House.
The results from both the first Hot2000 & PHPP software models are shown. Keep in mind, these are working models and will be revised as new information and design changes come into play. We won’t know exactly how low we can push the Thomas House at this point. Now, the results do differ as the software's output is calculated differently from one another. Regardless, both results maintain that the home's energy use and heating loads are low, much lower than conventionally built homes in Central Alberta! The first round of Hot2000 models show that we will consume 40% of total energy that a conventionally built Canadian home would. Final numbers are still being tallied.
As for the PHPP outputs, we've reached a very comfortable 19 kWh/m2 per year. Just shy of the 15 kWh/m2 heating load limit for PHPP standard certification. Honestly, in Alberta's climate, I'm satisfied with this result.
Now, for non-energy-modelling updates!
After searching high and low, we've finally settled on our windows. Before this process, we did not realize how much consideration windows required. Specifically, understanding the performance of the window glazing, frame and the spacer required patience and persistence when dealing with suppliers. I realize that in a lot of cases, suppliers did not thoroughly understand their own windows. Not all, but some. Getting into the details of the U-factor (W/m2), the solar heat gain coefficient (G Value), frame materials, spacer materials, orientation, visual transmittance, and of course, the price, required more effort than initially thought. One of the issues I found besides in some cases, a lack of knowledge, was determining the specific thermal rating of the different components. Some window specs provided by suppliers specified R-Value, some U-Value (metric), some U-Value (imperial), some with the overall U-Value, and the most informative, helpful suppliers provided the metric U-Value of the frame, glazing, & spacer independently. This made my job much easier when plugging them into the PHPP software. Further, quotes were provided in relation to what my plans specified, and could then be further altered to reduce cost & complexity while increasing performance through value engineering - basically simplifying the design. The output of this adjustment resulted in being able to have much larger doors than initially planned for, in order to eliminate the sidelights & transoms completely, which was OK with us! A huge front door will make things easier when moving in furniture and will provide some extra wow factor we didn't expect to include.
In the end, we are very sure we're choosing Internorm windows & doors, which the Canadian supplier is based out of Montreal and the product manufactured in Austria. European doors & windows are much different than North American ones in design and performance. We were drawn to their modern aesthetic and functionality, especially with the operable windows and sliding glass doors that maintain their seals very well. We compared almost 10 different suppliers, some local and some European, in order to determine which product met our needs best. As well, we'd like to give a shout-out to Internorm for their absolutely quick response times, friendly and very personal service while ensuring we could find a product that met our budget. It's definitely a concern purchasing a product you're not familiar with from someone across the country, imported from another continent, but this company has went above and beyond so far. All the windows, including the patio doors are triple pane, low-e argon filled (except the massive, well insulated front door!). Our south facing windows will have additional level of glazing in order to ensure we maximize the amount of solar radiation coming into our house to be used as free heat. As for budget, we were extremely pleased (and surprised) that they were able to be competitive with other quotes we received that were manufactured more locally, especially since the shipping alone is a larger portion of the window budget than we would have hoped.
For some additional information on choosing proper windows, check out this post.
This project has pretty much been 90% planning, and now it's almost time to start shovelling! Check back soon for further updates!