Site Planning

I’ve been working on Making the Value Proposition of Design lately and thought I go straight into what your designer might actually do for you.

More often than not an owner has property before they have an architect, builder, or designer. There have been instances, however, where folks are looking at several sites and have asked us for help evaluating various properties.

If you find yourself considering a few different properties, consulting with a designer and/or a builder can save you many thousands of dollars and make for a easier build and a better building.

To be perfectly honest, in Asheville’s overheated market, you may not have time to consult. In these all too common instances I’d like to offer the following thoughts on property evaluation for green building.

1. Location
This is so obvious it seems ridiculous to mention but where a piece of land is means more to the projects “green-ness” than just about anything else. If the property is way out in the sticks it’s going to take more energy to get workers and materials to the site than the same project in town.

Over the operational life of the building the energy required to get to and from the building and to keep the building serviced will far outweigh any environmental savings an otherwise green built building might offer.

The takeaway; if it’s down to two properties of otherwise similar features, pick the one closer to goods and services, etc.

2. Topography
Again, this is pretty obvious but let’s go over it anyway.

A “good deal” on a steep lot might not be such a good deal after all. The increased costs associated with grading, access, installing utilities, and maintaining a building on a steep site might very well be several times over the savings of the “good deal”.

Of course we live in the mountains and level lots are pretty much unheard of so here’s an idea. A lot that slopes about 10 feet in elevation over 30 feet of plan is ideal for a walk out lower level (notice I didn’t say basement because that, technically and practically, is a different beast). 10 feet over 20 feet (steeper) is doable but anything steeper than that is going to start adding up.

Some municipalities have steep slope ordinances that will require the consultation of geo-technical engineers. This can range anywhere from the minor cost of the consult to the tremendous cost of geo-technical interventions. Watch out for this one as it could really hurt you.

Btw, you can use the county’s GIS website to get rough topographical information.

3. Solar Orientation
Here’s where we begin to move outside the realm of the obvious (for most home-owners anyway).

Which way your property and hence your building faces has tremendous impacts on both the energy performance and the “experiential” aspects of your project.

For example, a north facing lot is going to be dark in the winter. This is especially true if there is a mountain or trees to the south that exacerbate the problem.

Not only does north facing offer less light it makes it almost impossible to harvest free solar energy.

The one caveat here might be an artist’s studio. Artist love the soft (weak) and in-diffuse light offered by a northern exposure.

The next cardinal point to avoid (if possible) is west facing. While it is possible (and even advantageous from a macro point of view) to harvest solar energy in the form of photo-voltaics it is not desirable from an experiential and performance perspective.

The setting western sun is hot. Usually, by the time the afternoon rolls around your building is up to operational temperature (it’s comfortable). Here comes the hot western sun to overheat your building, sometimes even in winter (Ouch! winter time air conditioning is hard to swallow).

Besides the energy penalty of west facing there is the issue of glare.

Glare is defined as “high contrast”. The human eye struggles to reconcile inputs of high contrast. Think of a dark stained window frame around a bright yellow setting sun.

It’s also hard to “crop” the western sun with porches and overhangs. No matter how big they are the setting sun, surrounding geography notwithstanding, is going to get under your architectural devices.

The takeaway. if you cannot avoid a west facing property (and they are commonly nice view lots) then consider going with a painted interior trim to minimize glare. Also consider minimizing window openings to the west.

South facing is commonly regarded as the most auspicious orientation from a building science perspective. It’s fairly straightforward to design southern roof overhangs to allow in the welcome winter sun and keep out the hot summer sun.

The final cardinal point is east facing. I’d give east facing a close second place to south facing. East faces the soft (softer) morning sun. Most folks like to see the sun as they get up in the morning.

If you like your house cooler as you sleep overnight then the passive solar energy of the rising sun is welcome as it heats you house to operational temperature naturally.

If a site faces east it still offers the opportunity to have a south facing roof slope that can be a platform for photo-voltaics.

3. Utilities
Make sure you have access to a sewer or enough land for a septic field and a repair area (to say nothing of the required clearance to a well if there is no city water.).

It’s nice to have access to grid electricity as well. Many folks are predicting that in the near future even this may not be required but that’s a story for another day.

4. Natural Features
What’s the potential for a view? What sort of trees and vegetation are on the site?

Cutting down big trees is expensive, stresses wildlife that depend upon these so-called keystone flora, and can lead to erosion problems.

A rule of thumb is if it is possible to stay out of the drip line (the outermost branches) of a tree then you can leave it. Remember this means no compaction of the soil in this area either so you can’t store materials there and you certainly cannot drive vehicles over the drip zone. Some trees are more susceptible to compaction than others so you might consider consulting an arborist.

Is there evidence of ledge on the property. Removing ledge is extremely expensive. An old timer who had done excavation for forty years once told me that mountain laurel prefers to grow in the thin soils covering ledge. If an otherwise healthy site presents with lots of mature laurel but not many other large vegetation it may be a sign of ledge.

Is the site chocked with exotic invasive plant species? If so, it’s going to challenging and expensive to get that stuff under control.

Look for a minimum of invasive species and you future gardening endeavors will be better served.

Is the property in a natural drainage area? If an entire mountain is drained through your potential property it is going to take a lot of design, engineering and construction to accommodate all that water.

So there’s a quick course in site evaluation that may help would-be green homeowners make the best decision.

Happy house-site hunting!

Steve Farrell