by Rachel Lyon, Editorial Director for The House Designers
You’re probably used to hearing about the latest and greatest products to help you create a more energy-efficient household, and while those are still critical to the overall picture, there are ways you can use your natural environment to your advantage as well. The simple orientation of a building has a drastic impact on sun exposure and affects daylighting and passive solar heating potential—both desirable, money-saving natural effects that you should take seriously! In the past, people were reliant on exploiting the land and sky to create comfortable houses for themselves, but the art and science of these skills haven’t been passed down to the average citizen.
The land and its exposure determine optimum house placement, and there isn’t a single solution that will work for everybody. Discuss your goals with professionals, and they’ll use computer models to find the best solution for your individual case. It’s easier to adapt a home to the land than the other way around, so here are some things to keep in mind as you examine lots and consider building your own house on them!
The Sun’s Position
For this discussion, we’re assuming a location in the Northern Hemisphere. The sun rises in the east and sets in the west, but latitude and the tilt of Earth’s axis over the course of the year constantly change its relative position. In the winter, the sun makes a low arc in the southern sky, and in the summer it rises higher overhead and shines from above around midday—and positioning the home to maximize southern exposure and limit northern exposure makes a huge difference for its efficiency throughout the seasons.
The goal is to capture as much direct sunlight as possible in the winter, and block it out in the summer, in order to lessen heating bills and naturally reduce indoor temperature, respectively. Think about orienting the home so its longest sides face north and south—so the lengthwise axis runs east-west—to make the most of this warming and cooling effect, but also consider the floor plan as a whole. You’ll want the most windows, and the most occupied living spaces, to face south to capture winter sunlight. The living room and kitchen are the obvious choices for this position, while less used areas are better suited to the north-facing side. Ideally, the garage and utilities can fill this place, because they will act as a natural buffer against the cold and the lack of windows means less inadvertent and needless heat loss.
If there are reasons you don’t want to severely limit north-facing windows—perhaps there’s a good view—you can overcome the summer sun by selecting a home with a wide, overhanging roof and making sure to install properly glazed and insulated windows. And if you're building at a lower latitude and are focused on staying cool rather than gaining heat, the more roof overhang, the better. It'll block the higher sun from hitting the windows year-round. Don’t forget to utilize the natural shade at your disposal, either!
The Effect of Topography
Mountains and valleys come with their own climate considerations, and they can also amplify the effect of the sun’s position. If you’re looking to build on a mountain, the ideal lot would be south-facing and about halfway up the slope. The northern side will be in perpetual shade during the winter, and choosing to go higher will expose the home to strong wind gusts. Choosing a lower position in a valley also can pose a problem, since cold air will sink into it, and there could be drainage concerns.
Of course, if you’re planning a residence that isn’t for year-round use, you can make your own rules. A north-facing mountain home can get plenty of gentler sunlight in the summer, and that’s perfect for somebody who is there to enjoy the land at its most hospitable.
Account for Tree Cover
Know your foliage! If you plan to build in a wooded area, knowing which trees are where will factor into the placement and/or orientation of the floor plan. Deciduous species, like oak, maple, and elm, lose their leaves in the winter, so they can be used to create shade in the summer without impeding the southern sun too much in the wintertime. On the other hand, coniferous trees, like cedars, pines, and firs, keep their needles year-round, and they are great to have on the west side of the home, where they can help block the strongest afternoon sun.
A builder can help you choose the optimum house placement, but you might want to consult with an arborist as well to ensure that the trees in the area are healthy and will remain so during construction. And don’t insist on building too close—not only do you risk damaging root systems, but they might do damage to your foundation, and you could find yourself cleaning leaf debris from the gutters too often for your liking. There are also local laws to consider, so check before finalizing plans.
If you’ve got multiple factors to consider when maximizing the passive solar heating potential of your home, and they don’t all fit together perfectly, don’t worry. You can orient the floor plan up to 20 degrees off the ideal east-west axis without negatively affecting heat gain too much. Just make sure you still have as many windows as possible facing the right direction. The perfect number of windows varies by location due to different climates and the fact that heat can be lost through them more easily than through walls, but choosing glass treated with special coatings can greatly reduce this loss and improve overall household efficiency.
The placement of exterior home features should also be taken into account. Take, for instance, the driveway. Made of materials that get very hot in the sun, its location relative to the house is certainly important. In hotter areas at lower latitudes, the driveway should be placed in a shady position so its built up heat doesn’t affect the house. Preferably, it should be on the east side, so the harshest sun doesn’t shine directly on it. On the other hand, a driveway on the south or west side of a home at higher latitude will actually be helpful, as it can encourage snow to melt and save you from excessive shoveling.
Home orientation alone has been found to have a large impact on efficiency, though the exact amount varies on location. Choosing the best windows, insulation, appliances, etc., will only increase these savings, so make your home as green as can be! While the upfront costs will be more, you will save over the years.