Some considerations to take into account when designing and planning a new home
*This article was adapted from Green Building Advisor https://www.greenbuildingadvisor.com/article/the-best-way-to-build
How important is energy efficiency? You should strive to build a house that is more energy-efficient than average. But while energy efficiency is a goal of residential design and construction, it shouldn’t be considered the highest goal.
Above all, you want your house to be functional and beautiful. Building scientist Joe Lstiburek has written, “In order for buildings to last a long time, people have to take care of them. … And guess what? People don’t take care of ugly things. Ugliness is not sustainable. … That is why beautiful buildings are important. That is why architecture is important.”
Your house should suit your family’s needs. You should strive to design and build a house that you’ll love. That means that it’s OK to design your house with a few idiosyncrasies and quirks, even if these quirks waste a little energy. For example, if you want a skylight over your bed, go ahead and include it.
Climate matters. A hot-climate house will have different features from a cold-climate house. Insulation levels are likely to be different, as will roof design, window size, and window orientation. When it comes to climate-specific design details, there is no substitute for informed local advice.
House size. A small house will be more affordable and energy-efficient than a large house. Moreover, for as long as the house is occupied, it will be easier to maintain and keep clean. Remember, too, that a small house will have a lower tax assessment than a large house.
House shape. Compared to a house with many bump-outs, a complicated or excessively large roof structure (i.e. an A-frame), ells, or curves, a house with a simple rectangular shape will be cheaper to build, and easier to heat and cool than a house with an irregular shape. If your building lot is large enough to provide flexibility on house orientation, the long axis of your house should be oriented in an east-west direction. That way, half of your gable roof will face south, facilitating the installation of photovoltaic panels.
As you plan your house, consider the sun’s daily path through the sky. Which rooms deserve morning sun? Which rooms need the most light? Which rooms need to be protected from the sun that streams through west-facing windows on summer afternoons? The answers to these questions depend on your climate and your personal tastes.
Foundation. If your building lot is flat, you’ll probably want an insulated slab foundation—a frost-protected shallow foundation or a raft slab. If the building lot is sloped, though, you should probably choose a basement foundation. (A basement doesn’t cost much more than a crawlspace, but it’s far more useful.)
Walls. In a cold climate, choose either a double-stud wall insulated with cellulose, or a 2×6 or 2x8 wall with a continuous layer of exterior EPS or polyiso foam. In a warm climate, code-minimum levels of wall insulation may be adequate, especially if your construction crew pays attention to airtightness and is meticulous with insulation installation details.
All walls should include a rainscreen gap between the back of the siding and the water-resistant barrier (WRB).
Airtightness. Everyone who works on the jobsite should be aware of the need to focus on envelope airtightness. The rule is, “If you make a hole, you’re responsible for sealing it.”
Airtightness details such as gasket installation and seam-sealing measures are best addressed as the frame is assembled and walls are sheathed. Once the drywall it hung, it’s too late for many of these details.
Most building codes now require new homes to be tested with a blower door. You’ll want to exceed minimum code requirements. A good target is 1.0 air changes per hour @ 50 pascals (1 ACH50). If your house is tighter than that target, congratulations.
Windows. Cold-climate builders should consider installing triple-glazed windows—assuming, of course, that the budget permits. If the budget is tight, choose double-glazed windows with good specifications. In warmer climates (Climate Zones 1 through 4), double-glazed windows are fine.
Plan your windows carefully. If your glass area is excessive, your home can suffer from glare, undesirable overheating, and excessive heat loss at night,. so consider each window carefully.
Remember, not every window needs to be operable. While every bedroom needs at least one window that meets emergency egress requirements, many windows can be fixed. Fixed windows cost less than operable windows.
Most windows should be shaded from the summer sun. Because west-facing windows are difficult to shade, they are major contributors to overheating.
Roof details. If you live in a cold climate, your house should have a simple gable roof without skylights, dormers, hips, or valleys. (That said, a hipped roof makes sense in a hot climate, since hipped roofs can provide shade on all four sides of the house.) Steep roofs are more forgiving of minor roof leaks than shallow-pitched roofs.
Create a vented unconditioned attic with raised-heel trusses, and insulate the attic floor with a deep layer of cellulose insulation. Roofing specifications will depend on your budget, but common choices include steel roofing or asphalt-shingle roofing.
Electrical system. Plan for an all-electric house. Even if your community has a natural gas distribution system, stick with electric appliances. The climate crisis requires all of us to limit combustion—including combustion of natural gas, propane, heating oil, or firewood. If you have an all-electric house, you’ll avoid the cost of hooking up to a gas pipeline, as well as minimum monthly fees charged by the gas company (fees that occur even during months when you don’t use any gas).
Photovoltaic system. If your budget is adequate, and if your local electric utility offers a reasonable net-metering agreement, you should plan to install a photovoltaic (PV) system on your south-facing roof or on a ground-mounted rack.
Plumbing details. Long plumbing runs between your water heater and your shower or sink will waste water and waste energy. Plan ahead so that hot water lines are short: if possible, cluster bathrooms near the kitchen, and locate the water heater near the important fixtures that require hot water.
Residential drain, waste, and vent (DWV) systems require a vertical vent that penetrates your roof. Make sure that your plumbing vent penetrates the north slope of your gable roof, not the south slope, so that the vent pipe doesn’t interfere with the installation of photovoltaic panels.
Domestic hot water. Since you’re building an all-electric house, you need an electric water heater. If your family doesn’t use much hot water, you might want to install a conventional electric-resistance water heater. Otherwise, specify a heat-pump water heater—and make sure that you decide at the planning stage where the water heater will be located.
There are several limitations governing water heater location. If you are installing a heat-pump water heater, the room where the water heater is installed has to meet minimum volume requirements established by the manufacturer. Ideally, the water heater will be located near the kitchen and bathrooms, but far enough away from bedrooms to eliminate noise complaints.
Heating and cooling. The best way to heat and cool an all-electric house is with a ducted or ductless minisplit system—that is, an air-source heat pump. If your home has multiple bedrooms, you can plan to install a ducted minisplit system for the bedrooms. While ducted minisplits can be tricky to install in an older home, they should be easy to install if you plan ahead during the design stage by providing a mechanical room near the bedrooms, as well as adequate ceiling height to install and hide ductwork.
If you have a two-story house with a simple floor plan, you should be able to heat and cool the first floor of your home with a single ductless minisplit head. This approach works better in a house with an envelope that is relatively airtight and well insulated than it would in a leaky house.
Ventilation. Every new home deserves an HRV or ERV with dedicated ventilation ductwork. During the planning stage, before the foundation contractor arrives at your site, you need to decide where the HRV or ERV will be installed, and you need to know how you’ll run the fresh air ducts and the exhaust ducts to the rooms that will be served by your ventilation system.
If you wait until the last minute to plan your duct runs, you’ve waited too long.
Siding. I’m partial to unpainted white cedar shingles or unpainted white cedar horizontal planking. But a different type of siding might look better in your neighborhood. If brick veneer is common in your region, it’s a reasonable choice.
If you install siding that needs to be painted, remember that as long as you live in the house, you’ll be locked into cycles of regular repainting.