Since I’ve been on the topic of site recently, here’s some thinking on the subject that I did for Digging in the Drifless a few years ago. Wise site choices can have a huge impact on the comfort and cost of a new building. Issues of solar gain, prevailing winds, and drainage are key, as well as more personal considerations like a favorite view all factor into this choice. Some of these issues can be resolved with a little websurfing and a good topographic map or aerial photo of the land (check with your local county surveyors). No matter what you find online, though, nothing can replace spending some serious time on the property, wandering the site and opening your senses. Finding the perfect building site is more art than science.
Here are some of the factors I try to remember as a designer:
MACROCLIMATE: How big is your sweater collection?
The internet is your best bet for this material. Do you need AC to survive the summer humidity (note that there are a number of natural building solutions for dry heat that don’t require any extra energy)? How much heat will your house need in January? Fix this data firmly in your mind and carry it with you as you move forward into design.
MICROCLIMATE: Your own little world.
Aspect: Aim south. If you are building on any sort of slope try to make sure it faces the south. Of course you want to take advantage of passive solar in your design and possibly incorporate solar hot water or even PV panels, but don’t forget the heat in the ground itself; a south facing slope gets the most perpendicular winter rays – which translates to the most warmth – which you can translate to your heating load in the winter.
Air Movement: Watch out for Frost pockets. In many ways cool air flows like water, rolling down hill, collecting in valley “streams” and then pooling up against obstructions (like your house), where it can create a “frost pocket.” This will kill your landscaping and up your heating load.
SLOPE: Be gentle on yourself.
A gentle slope is ideal. Very steep slopes can create more trouble than they are worth in excavation costs and complications, but the level parts of your property are often best used for other things like garden space and out door activity areas. (Remember Christopher Alexander?) Meanwhile your house can take advantage of an angle. Also, waste. Its an indelicate subject to bring up, but it is costly and problematic to pump sewage uphill. And the image of a pump stalled by power outage or mechanical failure is not pretty. Just one more reason to look for a hill side site – and plan your drain field down hill.
IMPACT: Minimize it.
Avoid blasting through bedrock as this is both expensive and environmentally unsound. Conversely if the soil on your building site is really great, consider moving the house and making that place into a garden. At the very least, move good growing soil mindfully and make use of it somewhere else after construction. And please, oh please, oh please don’t buy up and build on prime farm land, either individually or as part of a subdivision.
SOLAR ACCESS: Plan with your sunpath.
In the Midwest you’ll want sun in the winter and shade in the summer. (The design of the building will address this, of course, but if your site works with you rather than against you, so much the better.) Make sure that if there are any trees between your site and the sun, they are deciduous and will lose their leaves in winter. This can be the best of both worlds, offering cooling shade in the hot months and accommodatingly removing it just when you want to start collecting that solar energy in the fall. Consult a sunpath diagram to see how the sun will move through the day and year in your location.
DISASTER: An ounce of prevention …
Say it with me: Don’t build in a flood plain. Don’t build in a flood plain. Don’t build in a flood plain! (This is one more good reason to seek out a gentle slope). Ask old timers, check the public records, consult the FEMA maps and … don’t build in a flood plain.
In this age of extreme weather events (global warming, anyone) don’t tempt fate. 100 and even 500 year flood plains are being re-drawn in the last decade. This goes for the edges of cliffs in ‘quake country and for ridgetops in tornado alley. If you are in an area prone to wildfire, consider how roads, streams and open areas can be used as fire breaks to protect your house. Or, even better, don’t build in fire country.
GETTING THERE: Do you really want to focus on the journey?
This issue works at several scales. Within your site, the further your house is from the lot line, and the more circuitous your route from point A to point B, the more land you must disturb and the more costly your driveway will be to build … and to maintain. Likewise, the farther your property is from civilization, from groceries, from work, from family and friends, the more fossil fuel you’ll burn getting there and back. Weigh your desire to get away from it all against your future fuel consumption.
BEING THERE: Use your senses.
Last but by no means least, experience the place. Nothing but time will do this for you. Stand in the building site. What do you see, smell, feel and hear? (Don’t taste anything unless you’re pretty confident in your back country skills.) Do this at multiple times of day and through a year or more if possible. What are your favorite views? Can you hear trucks on the highway or see your neighbor’s blinding security light at 3 AM? Think about how moving your building site around may shield you from the bad and enhance the good.
Note: My experiences and opinions here on Dwelling Places will primarily be addressing the climate and site and design issues of the upper Midwest. There are excellent sources of planning and design materials for every region in the country available in book form and on the internet. I have (for the most part) focused on the design principals and techniques best suited to this climate. The importance of a place-based design culture cannot be over estimated.