Flatrock Passive: A Garden and a Sun Shade

first_imgEditor’s Note: This is one of a series of blogs by David Goodyear describing the construction of his new home in Flatrock, Newfoundland, the first in the province built to the Passive House standard. The first installment of the GBA blog series was titled An Introduction to the Flatrock Passive House. His most recent post was Taking a Tour. You’ll find his complete blog here.   This year, summer got off to a bad start. June was cold, with an average temperature of around 7°C (44.6°F), accompanied by a lot of cloud cover and drizzle. I have realized over the past 10 years that outdoor living in Newfoundland is really limited. Summer is short and you really don’t have a whole lot of time to enjoy it.RELATED ARTICLESA Quantitative Look at Solar Heat GainWindow Shades, Blinds, and AwningsDo Window Shades Save Energy?Green Landscapes: Native Plants and SoilResilient Food Supply Systems For this reason, I planned on using the outdoor space quite differently than at my previous property. I also wanted to make sure that my time in the garden had some payback. I decided that a good place to invest my time and effort would be a landscape that offers some food security. As well, I wanted a low-maintenance landscape that grows well in our environment, and is resilient to drought and pests. My plan for landscaping was quite simple really: Go back 50 years and do what most Newfoundland families did. They grew root vegetables. Good cold-climate varieties that are tuned to our short growing season are easily accessible, and they can be stored for long periods of time under the right conditions. With the right plantings, you can get multiple crops out of the same plants. With this in mind, we decided to grow onions (160 plants), turnips (120), carrots (300), beets (100), cabbage (20), parsnips (100), and lettuce (who knows!). We also planted some herbs that lend themselves well to drying for winter use. Potatoes are a staple here, and luckily they are dead easy to grow. Our vegetable garden takes up the whole back yard! Winter storage With all the vegetables and about 180 potato plants, creating long-term storage was a necessity. I designed and built an underground cellar which sits in a slope on the east side yard. It is basically a concrete bunker with a structural slab sitting on the top. The whole thing was tarred on the outside and a pond liner was draped over the top to help shed water. I installed some leftover 4-inch EPS foam insulation on the top of the slab because I wasn’t sure I would be able to backfill the cellar with enough soil to ward off frigid winter temperatures and the heat of summer. The thermal properties of various soil types is pretty complicated. This being said, there appears to be a consensus that the R-value varies between 0.1 to 0.25 per inch. Adding 4 inches of foam is equivalent to adding many feet of earth. It doesn’t add thermal mass, but it is much easier on your back than shoveling a couple of  loads of topsoil! We added about 2 feet of earth on top of the cellar and I plan on seeding it with grass sometime soon. I still have to build some shelving but there should be no problems having this ready for winter. An underground root cellar is protected by earth and 4-inch-thick EPS insulation. During April and May, I finished several larger projects: I added a small deck for the back entrance and a veranda under the front overhang. The driveway is now paved and the front yard is now being landscaped. I am hoping to seed this week with timothy grass, white clover, and red clover. Things are shaping up nicely. Summer comfort and energy use As for energy use, our usage for the month of June 11- July 11 was 651 kWh. Given that the average June temperature was 7°C, I felt that this was fairly respectable. The heating system ran about two days altogether. With the heating season over, I can safely assume that this is approximately the baseload of the building. I have installed a Nyle Geyser air-to-water heat pump that helps with some cooling and dehumidification while maintaining the temperature of the Logix24 boiler tank for hot water use. The unit pulls warm air from the living room, into the heat pump, and pushes cool air upstairs. The cold coils capture some latent heat and the condensed moisture is drained into a floor drain. In short, the Gyle captures heat from the air in the house and cools it in order to heat the hot water for the tank. Overall, the house temperature has been fairly constant. There have been a few days when the outside humidity has been so high that it led to increased humidity inside the house. I had the ERV set on continuous ventilation and didn’t realize it. This was a huge mistake. This made the building very stuffy because of all the humidity, although the interior temperature has been fairly constant. At one point, the temperature inside the house was about 23.5°C (74.3°F), which is well under what Passive House considers an overheating event …. however, the humidity has varied quite a bit. Humidity as high as 80% has led to apparent temperatures of about 29°C (84.2°F) or higher! Humidity plays a huge role in comfort. So I have been playing with nighttime flushing by opening windows during the night and closing them in the morning. That has been somewhat effective. Even though I don’t mind opening and closing windows, I can see how it wouldn’t be convenient for most people. There was a bit of a learning curve to determine how much to open our windows. Our location is so windy that the wind can blow the screens out of the windows! It would be nice if the night purge was more automated. I find myself looking more at the weather forecast so I can time opening the windows with cool temperatures and low humidity, only to wake up and find it has rained and the air coming in the house is at 95%+ humidity. The smart mode on the ERV tries to save energy by limiting ventilation when the temperature outside gets too hot. During this time it recirculates air throughout the house. I have found that having the recirculate mode set to 100% of the motor capacity helps with moving some cool air around. Some HRVs have the ability to bypass the core to cool the home when exterior air is cooler. My ERV does not. This is one feature that I wish our unit had. However, ventilation CFMs are usually not high enough to cover the cooling loads required, so the extra money spent on the fancy ERV with bypass may not have worked out anyways. For now. I’ll stick to opening the windows! Building a window shade Earlier in the summer, my first project was adding a shade structure to several windows on the main level. The WUFI model showed some overheating in the middle of summer without the structure in place. Before we installed the clapboard siding, I had attached vertical ledgers (I call it a vertical ledger board) so I could secure braces that would be used to attach the shade structure (see the first image in the gallery). My design uses a set of 90° brackets secured to the vertical ledgers. Rather than 2×6 slats specified in the original drawings, I decided to use 2x3s. The shading provided when the sun sits lower in the sky would be different, but with some investigation on paper, I determined that one could space the 2×3 closer together in order to get a similar effective shading. I built the brackets in my workshop and stained them white to match the trim on the house. I lifted the brackets in place from a ladder and secured them to the house. I leveled the two at the ends and attached a string line between them. The two in the middle were lifted up in place until they just touched the line and then they were secured. Each bracket is secured with a six 8″ x 3/8″ lag screws. Once the brackets were installed, I measured and cut all the components,  i.e. 2×6 joists and 2×3 slats. I stained all the parts in my workshop. The structure went up once piece at a time. The main joists were lifted in place from a ladder. They were then secured with #10 5-inch plated screws. Laying out the slats was first done on paper. As I added slats, I checked the remaining distance and made small adjustments to spacing so there would be slats at either end (see Images #2 and #3 in the gallery). The shade structure definitely makes a difference to the solar irradiance inside the house. I estimate that the shadow it casts is at least 40% of the total illuminated area. I have noticed as we moved into June that the main level doesn’t heat up as quickly as it did a month before. June has been cold so the solar gains would have been nice, but the model uses average climatic data, so performance is based on an average rather than a specific weather pattern for the given year. The most difficult part of the installation was moving the heavy ladder around. The job was fairly time-consuming, mainly because of the number of times I had to climb up and down the ladder. That being said, the exercise really warmed me up on those cold days of May.last_img read more

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