Temperatures are rising! From a cold spring, diving feet first into the first hot weeks of the year. "So isn't your house like a sauna with these high temperatures and all those windows facing south?" - a question I get a lot.
Actually, its quite the opposite and its been surprisingly cool despite not having any blinders on the windows, or shade from trees or buildings near me. I haven't used any fans or had to be concerned about strategically opening/closing windows throughout the day. There's a few basic, yet unconventional principles that are core to what make this house a future-proof palace. Hot summers are increasingly common in the northern hemisphere so I hope these principles will become more the norm.
1. Insulation: Especially for cold winters, but also helpful for hot summers, it is beneficial to have a high insulation level. Depending on the material used, you can calculate how thick the walls need to be. This is part of Dutch regulation and since I used straw for insulation (locally produced and not manufactured), the oficial calculation resulted in 28cm thick walls. According to Strobox, the official calculation is actually unfavorable for straw, so in reality the insulation level is higher. I added another 40mm woodfiber insulation to all internal walls, and to the south facing wall 80mm (40mm inside, 40mm outside).
2. Thermal mass: Most people aren't aware of the difference between insulation and thermal mass. While the first prevents the outside temperature from affecting the inside temperature, the second maintains a stable indoor climate so that when you open a door or a window the temperature isn't instantly affected. In my case, the walls and floor combined hold about 4.000kgs of earth (cob) which seems to do the trick! Especially the earth rammed floor, which is around 8cms thick.
3. Solar glass: When I refurbished the used windows (dating from 1984), I replaced the glass for high quality glass with solar specs. The low winter sun is let through while the high summer sun is reflected. Its amazing to feel how little heat penetrates the windows right now, even in the middle of the day!
4. Solar panels: An overhang from the roof, or in my case a row of solar panels, help provide shade on the walls and windows. Just like the point above, the low sun can hit most of the south facing wall in winter to help warm the house, whilst they provide shade when the sun is up high in summer (see picture at the top).
5. Heating/cooling system: Besides the above passive elements, there's a back-up system which can cool the house very energy efficiently. The heat-pump which generates hot water for the floor heating in winter, can actually cool the floor too. And because of point #2, all it needs to do is to circulate cold water which lowers the temperature of the earth floor. I'm curious as to when I'm actually going to need to use it as summer progresses.
All-in-all a very comfy place to be and I invite you to visit on a warm day to experience it for yourself!