Residential upper floor addition in Woodinville, WA with polyisocyanurate insulation, stack ventilation, and clerestory lighting...oh and solar panels.
You want to be green and live sustainably. That's a good thing. Solar panels tend to be considered the most sustainable thing you can do to your house. Why is that so? There's 2 reasons: they are visible...you can see them from the street, and everyone can admire them. Ooooo, ahhhhh...nice panels ya got there! The other reason is they are cool. The sun hits them, and electricity is magically made.
Although they are perceived as the most sustainable feature, are they really? If you evaluate the facts, they are really one of the least sustainable things you can do on the list of green design and construction principles. They are still a good thing to do, but let's discuss things you should do first BEFORE installing solar panels.
Caulk. Don't get too cocky about your solar panels unless you first get caulky with your caulking gun. Typical construction has a lot of gaps. Each time a window or door is installed, the builder essentially cuts a hole in your house. Each time a water line, sewer line, electric line, vent duct, etc penetrates through your house, those are more holes. When plywood is attached to the stud walls, there's minute gaps between the panels. When a sill plate is attached to the top of a concrete foundations, there's more gaps. You get the idea. There's gaps EVERYWHERE in construction, and those need to be filled. These gaps enable the unwanted air infiltration. Heat travels from areas of warmth to areas that are colder. That's just the way science works. So, in the winter, you pay a bunch of money to heat your house, and that warm air leaks through all these gaps. In the summer, the opposite thing happens. Caulking, otherwise known as "air-sealing," will prevent the majority of this heat loss which saves a dramatic amount of energy.
So what does caulk have to do with solar panels? Well, caulk saves energy, and solar panels make energy. Compare the cost of a $5 tube of caulk, and the cost of a $1000 solar panel. Next compare the amount of energy a tube of caulk can save to the amount of energy a solar panel actually makes. Lastly, compare the embodied energy of a tube of caulk to the embodied energy of a solar panel (embodied energy is the total amount of energy used to manufacture, ship, package, etc a product). A solar panel saves/creates nowhere near as much energy as a good caulk job. Every building, building material, and building site is different, so I cannot cite specifics, but the energy leaking out of an un-sealed building is far more than the energy created by a few solar panels. My advice is to caulk every seam and tape every joint with an air-sealing tape during (or after) construction. This will give you much more energy savings. (Or you could just buy solar panels to create energy, and let that energy leak out of your house). Would you expect a fancy North Face coat to keep you warm with the zipper still open during the next winter blast?
Another significant green construction strategy that should be done BEFORE investing in solar panels is upgrading the insulation value of your house. This is a major savings. As previously discussed, heat travels from areas of warmth to areas of cold. So, even if you do have a tightly air-sealed house, the next easiest place for you to lose energy is through your walls, floors, roofs, windows, and doors. The building code requires certain insulation values for all of these items, but energy still leaks through unless you surpass the requirements. A simple strategy is just to change from batt insulation (the fluffy pink stuff) to rigid foam insulation which comes in boards or can be sprayed as foam. Within the same thickness of wall, roof, or floor, you can more than double the insulation value by switching to rigid insulation. Closed cell spray foam polyisocyanurate insulation can give you about 2.5 times the insulation value as the regular pink stuff. This means you are saving 2.5 times the amount of energy because you aren't allowing it to leak through the building. Is a solar panel going to MAKE 2.5 times more energy than your house wastes? No.
Another strategy is to layer insulation. You can use the less expensive batt insulation as usual, and on the exterior surfaces of plywood, you can additionally cover those with foam board insulation. One side of the boards is even covered with foil to help reflect the heat back inside. The foam boards are like a winter coat wrapped around the building, and these can also be caulked and taped to really trap the heat in. (In the summer, this also traps the heat out to keep the indoors comfortable). There's also more advanced strategies such as overlaying wood strips between several layers of insulation since heat has a hard time traveling from a solid, then through air, then through a solid again. There's also a lot of other strategies for lighting, heating, cooling, ventilation, water saving, etc that you can do to save a lot of energy too.
The moral of the story is to FIRST SAVE as much energy as you can before you start making more energy with solar panels that will just be wasted again since there's so much more savings of energy when compared to creating energy with solar panels.
Once you have installed all the energy saving strategies, lets talk about solar panels! I know how to get the power company to buy that energy from you for double the regular selling price.
This article shares more info if you’re interested: https://raystowatts.com/solar-generators-for-homes/
If you’d like to learn more about our design process, visit www.josharch.com/process, and if you’d like to get us started on your project with a feasibility report, please visit www.josharch.com/help