Like most people I want to be more environmentally responsible. I recycle, turn my thermostat up in summer and down in winter, and turn off the water when I brush my teeth, everyday actions that I hope have a collective impact.
When I started designing the Garden Home Retreat I wanted to make the house as green as I could. A combination of discovery, sense of adventure and dedication has all come together to create a home that hopefully serves as a model and inspiration for others. By working with the existing landscape as well as keeping our key goals in mind, the Garden Home Retreat will demonstrate how a traditional architectural style can successfully merge with the idea of living lightly on the land.
In designing the cottage, I focused on two key elements: energy efficiency and user compatibility. Energy savings is achieved through several fundamental changes in how the house is built (wall systems, mechanical systems, site orientation, indoor air quality, solar thermal water pre-heating) as well as making smarter choices on smaller levels that have a cumulative impact (water saving plumbing, graywater recycling, rainwater catchments, compact fluorescent bulbs, engineered lumber, green cleaning products).
A Systems Approach
One key lesson we learned about the green building method is the value of taking a "systems approach" to things. It doesn't work to simply plug in a few green components here and there and expect to see much impact. By systematizing things you end up with a simple but efficient series of components well-suited to each other. Thinking of the house in these terms, we first tackled the building envelope. Not only does this outer skin serve as the framework of the house, its efficiency — or lack thereof — plays a big part in the impact the dwelling has on the environment, the comfort and health of the occupants, and demands placed on the mechanical systems.
At the basement level, the walls are constructed using Amvic's insulated concrete forms (ICFs). The lightweight forms are made from expanded polystyrene (EPS) that will absorb and store heat, as well as eliminate drafts. Since the forms are so light, less fuel is used in shipping them to the site. Easy to install, the ICFs eliminate the need for a vapor barrier and the plastic webbing that separates the faces of the forms is composed of recycled plastic. The webbing is also designed to act as an attachment point for the interior and exterior finishes, thus saving the wood or steel that would be used to fur out a conventional concrete or CMU basement wall. Once filled with concrete, the ICFs create an extremely energy efficient and durable wall that provides safe shelter against tornadoes, earthquakes and wildfires — all issues at our site. In fact, in one portion of the basement I used the Amvic ceiling system and created a FEMA-approved storm shelter.
On the main floors of the house, I chose more conventional wood stud walls constructed from Southern pine, which is a fast growing and renewable forest product in our region. When large dimension support was needed, I chose engineered lumber from Southern pine instead of old growth lumber. Inside the walls, Rehau PEX tubing replaces copper water lines and also serves as a domestic fire protection system. The spaces between the studs are sprayed with Biobased insulation, a soy-based spray foam that not only provides superior R values, but also acts as a vapor barrier and seals off the wall, preventing drafts. On the exterior, Tyvek ThermaWrap combined with a 2-inch air space behind the durable brick veneer, adds additional R value while preventing moisture buildup within the wall cavity.
Putting Nature to Work
Additional energy savings come from the site itself. The orientation of the ridge fits perfectly with a layout that allows for cross ventilation and natural light. The house is positioned to take advantage of the remarkable views and the prevailing breezes. All of the major rooms and bedrooms have energy efficient Marvin windows on at least two exposures to facilitate cross ventilation. Inside the cottage, high ceilings are a tried and true Southern approach to dealing with the heat of summer, and tall Marvin windows allow the natural light to penetrate deep into the rooms. The north side of the house looks out over the river valley and has a series of porches that will serve as outdoor living rooms. Shade trees offer protection from the summer sun, and screened windows allow winds to cool these indoor/outdoor settings. On the second floor there is even an old fashioned sleeping porch.
During construction, the most challenging aspect has been the lack of potable water. The site is off the city water supply and we are dependent upon wells for drinking water and irrigation. While the supply of well water is abundant, it requires treatment to be safe for household use. Because of this, we were compelled to learn about rainwater harvesting and graywater recycling. By doing this we will be able to significantly reduce the amount of treated well water required for irrigation. An added benefit is that the rainwater is significantly better for the plants.