Which Building Techniques Are Used In My Design?
- Extra Insulation all around the house reduces the amount of heat that can escape the house during the winter and enter the house during the summer, lowering energy use related to heating and cooling the house.
- Insulation inside the concrete slab foundation. A 2″ layer of rockwool lines the inside of the footing stem walls and a 2″ layer extends horizontally under the slab foundation on a 2 foot perimeter around the entire foundation.
- Exterior walls studs are 2×6 spaced every 24 inches as opposed to most standard construction consisting of 2×4 studs spaced every 16 inches. The wider studs make a thicker wall and combined with the greater spacing betweeen them create more room for insulation inside of the wall.
- Studs are capped with a single top plate reinforced with metal brackets as opposed to two plates in standard construction. Less materials and more room for insulation.
- There are no pipes inside the exterior walls. Almost all houses have pipes for plumbing inside the exterior walls, as well as ductwork for heating and cooling. All of the plumbing and ductwork for my house is located on interior walls, again creating more space for insulation inside the exterior walls.
- A fully continuous 1″ layer of insulating foam panels surrounding the walls of the house. Most houses have no insulation at the stud locations, creating what is known as a thermal bridge where heat can easily escape the house during the winter and enter during the summer. The layer of foam effectively blocks the thermal bridge.
- Full 15″ inches of attic insulation from eave to eave. The part of the house where the roof slants downward and meets the upper wall is known as the eave. In many houses, the attic near the eave contains less insulation than the rest of the attic because there is no room between the roofline and the ceiling of the house. My house is built with “energy heels”, meaning the upper wall of the house continues vertically above the ceiling before meeting the roofline so that the layer of attic insulation is the same across the ceiling of the house.
- The only area of the house where I have equipment in the exterior wall is for the main electrical panel (again, more room for insulation). This particular area is located in a closet and will receive an extra layer of insulation on the inside of that exterior wall, ensuring the amount of insulation is consistent on every section of wall.
- All insulated areas are well ventilated and allow for any moisture to dry to the outside as most insulation doesn’t work well when it is wet.
- Most homes have siding on the exterior wall to protect the insulation from water damage, but this siding is attached directly to the wall and allows literally hundreds of pathways for pressure differences to force water into the walls. My house has 1×4 furring strips that attach to the wall and then the siding is then attached to the 1×4 furring strips. This creates an air gap between the siding and the wall to make it more difficult for water to pass between the layers and to help dry out any moisture that ends up between them.
- Vents at the eaves of the house allow air to enter the attic and pass through a gap between the attic insulation and the roof line. The air flows over the insulation, again, helping to dry out any moisture that finds its way in there. This air then exits through a vent that runs across the entire length of the top of the roof, or ridge.
- Moisture on the interior of the house is controlled by an energy recovery ventilator, which continuously brings fresh air in from the outside and exhausts it from the inside, while simultaneously exchanging moisture and heat between the two air streams. This ensures that humidity in the house remains relatively consistent.
- The windows and doors I installed are extremely efficient at keeping heat in while also allowing sunlight in. The majority of my windows have a U-value of 0.15. Energy Star guidelines call for a U-value of 0.27, so many of my windows have almost twice the insulating power of what is already considered by the government to be an efficient window. All of the south facing windows have a solar heat gain coefficient of 0.39, which is the highest I could find without sacrificing the U-value. This means the windows will absorb sunlight, which will provide heat for the house.
- The house is thoroughly air sealed on all 6 sides to prevent heat transfer via convection. Convection is the method heat is transferred through the air. Most houses have many pathways for air to enter and exit the house through small, unsealed penetrations in the walls. In fact, quite a few builders think it is important for houses to “breathe”. This is preposterous because humans certainly don’t breathe through their skin, they breathe through their nasal passage. Likewise, a house should breathe through it’s ventilation system, not its walls. A huge amount of heat can escape in this manner, so again, eliminating it can reduce energy used to heat and cool the house.
- A concrete slab forms an air impermeable layer at the bottom of the house, which is sealed to the bottom plate of the four walls by a layer of caulking.
- These bottom plates are then caulked to a layer of air impermeable plywood sheathing that surrounds the walls. The edges of these sheets of plywood are both taped together and caulked to the studs beneath them. Seams between windows or doors and the plywood are also caulked and gaps between the framing is filled with air impermeable foam. Any electrical wiring or air ducts penetrating the plywood is surrounded with a layer of air impermeable expanding foam.
- The plywood is caulked to the air impermeable rim joists and foamed on the inside as well, ensuring a continuous air barrier from the first story to second.
- The second story plywood layer is caulked to the top plates of the walls, which are then sealed from the attic with expanding foam to air impermeable ceiling drywall. The seams between the drywall are taped and covered with air impermeable joint compound. All electrical penetrations through the ceiling are surrounded with expanding foam. All utility penetrations through the top plates of the walls are likewise surrounded with expanding foam.
- A secondary air barrier is also formed by the gypsum board covering the walls. This is caulked to the flooring and attached to the ceiling drywall with joint compound. It is also caulked to all penetrations including doors, windows, electrical outlets, etc. The drywall is continuous along the exterior walls, running behind the interior wall studs. This means fewer joints where air can escape.
- The home is heated with the most efficient air to air heat pump available on the market today. If you don’t really know what a heat pump is find out here. A 3/4 ton Fujitsu mini split with a 14.2 HSPF rating (BTU per watt hour). This unit provides the most amount of heat per watt of electricity that you can find on the market today (although air to water heat pumps are more efficient). For example, the government considers anything above 8000 BTUs per kWh as very efficient, yet this system is able to provide 14200 BTUs for the same amount of electricity.
- Heat pump performance varies depending on outdoor temperatures, so the numbers above are just for reference, but even if it is 24 degrees Fahrenheit outside this unit would be capable of heating my house to a comfortable 70 degrees, according to my Manual J calculations. The coldest temperature in history in the Vancouver BC area is 26 degrees Fahrenheit.
- I will most likely never use air conditioning since I am so close to the coast, but if needed, the unit is also the most efficient air conditioner in it’s class as well.
- The water heating system is also one of the most efficient systems available on the market today. Much like the system that heats the air in the house, the water heater uses a heat pump to draw heat from the outside and uses it to heat the water. It is almost 4 times as efficient as the average gas or electric water heater.
- The water heater is located towards the center of the house to reduce the distance it needs to travel to get to where you need it. This also eliminates wasted water while waiting for the hot water to arrive.
- Whereas most houses are designed by architects who tend to focus primarily on aesthetics, I designed my house with a focus on engineering. It may not be the most jaw dropping house on the block, but it certainly won’t be an eyesore, and it will be by far the most efficient.
- For example, although the lot is situated so that the north side of the house is the front, there are only two windows on that side. When you have an engineering mindset, a window really only has two purposes: allowing sunlight into the house to warm and please the inhabitants, and to look out of. The north side of the house won’t get a lot of sunlight and it has the worst view, so windows really aren’t important there. I also designed the house so areas that are either not used much or are only used at night are on the north side of the house (bedrooms, closets, bathrooms, etc) The south side of the house is reserved for living room and kitchen since those are areas you spend more time in during the day.
- The design of the house is a simple box. This not only reduces the amount of materials needed to build, but also reduces the amount of exterior wall area where heat can escape. The house is longer on the east-west axis to maximize exposure to direct sunlight from the south both to power the solar panels and to passively heat the house.
- Every appliance is one of the most efficient on the market. From the induction stove to the condensing heat pump dryer, I picked out every appliance from Energy Stars top picks.