If your goal is to build an efficient house the devil is in the details.
Not paying close attention to the little things can result in a lot of little inefficiencies. if you expect the lifespan of a house to be in the 200 year range, these little inefficiencies add up to a lot.
The main concern here is energy efficiency, but I also want to touch on construction efficiency and on living efficiency. By living efficiency I mean time, money and effort spent on maintenance as well as everyday cost in time and effort.
One of the factors I have probably mentioned too many times already, is size. It is only common sense that a larger home is going to be less all around efficient than a smaller one built to the same standards. If prestige is the goal, my feeling is that there are far better ways to gain it.
Very careful planning is where efficiency starts. Use care and common sense in evaluating your needs. Think into the future. Are you building space for children that will be gone in a couple of years? Are you considering special needs you may face as you age.
Keep it simple. Complicated designs tend to have higher costs and contribute to both energy and construction inefficiencies.
A simple rectangle is the most efficient design for energy efficiency. It provides the most space with the least exterior surface.
The insulating value of the walls and especially the ceiling is very important if you live in a cold or hot climate. If you are lucky enough to live in area where daily average temperatures stay in the comfortable range then thermal mass is probably more important. The ceiling is easier to insulate to higher R values and has a reasonable payback even to R50 and higher. Most homes have a certain amount of heat layering which increases the temperature differential between inside and out at the ceiling and the tops of walls. More insulation is required at these locations for the same results. Blow in insulation works well. Normal rafter configurations make the area above exterior walls difficult to insulate well. Special rafters with a raised “heel” solve this. The extra cost may be worth it. How to measure heel height.
Rafters today are usually manufactured trusses which are enable fast and efficient construction. Click here for a truss diagram and a glossary of terms. A n excellent and more detailed explanation of trusses is available here.
When calculating paybacks it is important to remember that fuel and electricity will likely become more expensive in the future. This will be partly because of scarcity and of environmental concerns.
Heat in the attic is not your friend no matter what your climate. Be certain of good insulation and ventilation. Choosing a light-colored or reflective roof covering could be beneficial.
Even the best windows have poor insulating properties. Design with this in mind. Don’t neglect the use of natural light for energy savings.
A two-story house or a basement can add living space at a lower energy cost. Providing staircases can reduce this benefit considerably. Stairs can be problematic for small children and seniors. There is an element of danger to everyone. My own opinion is that it is best to avoid the risk of falls if possible.
One of the most common housing problems I have encountered over the years, has been wet basements. Providing a full depth basement that is completely waterproof may be more costly than the space is worth. This link is to a commercial site, but they do list a lot of the common basement problems.
An efficient house must be as impervious to air movement through the exterior envelope as possible. Pay extra attention to sealing around windows and doors. Don’t forget to seal where plumbing and wiring penetrate the building envelope.
Energy efficient lighting is a consideration. Flourescent and LED lighting uses less electricity than incandescent. In a climate like much of Canada it becomes a little more complicated. incandescent bulbs lose efficiency by generating heat. In winter, in Canada, that heat is definitely not wasted. In summer the days are long and little light is needed. Other considerations are how that electricity is generated and what fuel you use for heating. My own guess is that the extra cost of flourescent or LED bulbs may not be justified in all cases. Our government here is taking the decision out of our hands by prohibiting the sale of incandescent bulbs. Probably an effort to make Canada look better to the rest of the world through climate change action. Follow your own consience.
Choose energy-efficient appliances. Front loading washers are presumably more efficient than top load. The capital cost, however, appears to be almost double. They do use less water and the cost to heat that water is, of course, lower. There is little reason to heat the water to wash clothes, though, so much of the advantage is lost. I think the jury is still out on this one.
A clothesline is an inexpensive way to use less electricity
A garage may seem like a bit of a luxury. Actually a lot of fuel can be saved by not having to warm or cool your vehicles by idling. An attached garage has at least one less wall for heat loss. There is no reason to heat a garage above 40 degrees fahrenheit. The latent heat of a vehicle just off the road is enough to provide most of the heat needed for a well-built garage. In hot climates, just keeping the sun off your car makes a huge difference.
Design your house for safety and ease of use. Make certain that bathrooms are easily accessible from all areas, Kitchens must be designed to reduce workload. Large closets are good in the master bedroom, but do you really need them in guest rooms? I never could see the logic of two sinks in a bathroom. Do you really want to carry togetherness to that extent.
Minimize hallways. They are largely wasted space. Do not use doors where they are not necessary.
Place windows higher for privacy and to maximize space for furniture.
Do not use more interior walls than you need. An open concept is efficient and pleasant.
To reduce the environmental cost of building your efficient house, there are a few considerations. Cement and steel are huge greenhouse gas producers so it follows that they should be used carefully. Calculate carefully so as to not waste concrete. Building on a crawl space reduces the need for concrete and reinforcing steel considerably. Both products have a long life and this reduces impact somewhat. Review each material and design choice for its energy use and environmental impact. Environmental cost of building materials.
Source as much of your material as possible locally, to reduce the impact of transportation.
Build strong and build in safe locations. Replacing or repairing homes damaged by flood or storm is not very efficient or environmentally friendly.
Use labor and trades that are nearby if possible. If doing much of the work yourself, see if it is possible for you to live on site during construction. This is a huge time and energy saver.
Choose your water and space heating equipment carefully. Eliminating a chimney saves considerable space and material. consider the space used by the equipment. Using a tankless water heater for both space and water heating eliminates the need for a chimney and much of the space requirements. Follow the following links for more information. Hydronic radiant heating. Heating with a hydronic radiant system.
Finally, the home that has a long practical use is more environmentally friendly, So build well and with forethought. Avoid fads.