Sunday, October 30, 2011

Passive Solar Heating

Passive solar heating is one of many scientific approaches the Miller home design uses in order to be more energy efficient.

When the leaves have come off the trees, winter sunlight shines on dark tile flooring and helps to warm the room. In the photo, the room is shown in the warmer months, when shade from the foliage and the more overhead angle of the sunlight is preventing the tiles from absorbing the solar heat. This keeps the room at a comfortable ambient temperature for the warm season.

The tiles are laid on top of an extra thick slab for insulation. A radiant heating system is installed in the ceiling. This is different from the more commonly seen radiant floor systems, so that the benefits of the passive solar heating can be realized. If a more common in-floor heating system had been used, the solar benefits would have been wasted, as the tiles can only hold a certain amount of heat (just as a battery is only able to hold a certain capacity of charge).

Low-E (low-emittance) windows are double panes of glass with argon gas occupying the space in between. The gas reduces heat transfer better than air. These are used on north, east and west facing windows. A special coating is added to these on the south facing windows, designed to reduce heat loss while admitting high solar gain. The use of windows has the added benefits of utilizing natural sunlight rather than energy-consuming electric lighting.

Careful attention to provide a well insulated space, as highlighted in the previous post, is essential for retaining the heat gained in the passive solar techniques. Additionally, although there is a small climate control unit, the Miller family notes that the insulation was so effective that the room stayed cool and comfortable during the summer. The cooling unit would only be needed for a group gathering.

Thursday, October 27, 2011

Insulated Walls

The Miller renovation was an exciting project to be involved with for many reasons. The scientific approach involved in combining different products to achieve the best possible benefits for both the Miller's home comfort and their concerns for the environment was especially interesting.

One of the priorities established in the Miller home renovation project was high quality insulation. This was achieved using various products, like the SIPs (oriented strand board on both sides of a foam core) in the roof structure that we highlighted in our recent newsletter. Another pre-engineered product is the highly insulated Thermomass wall we used in the foundation structure for the rear walk out basement level of the home.

Thermomass walls consist of 4" thick Styrofoam panels, sandwiched between two layers of concrete (a cross section is shown in the photo). They are held together by a fiber composite connector, and the exterior provides waterproofing. The end result is an incredibly strong structural component that is virtually weatherproof and has a high level of thermal resistance. The Styrofoam core is recyclable, too.

Another insulation product incorporated into above ground portions of the walls is a foam spray. The quantity required depends on the climate in your geographic area, as well as the part of the home to be insulated. An American company called Foam It Green is a manufacturer of this type of spray insulation. Like Harmon Builders, the company is a member of the U.S. Green Building Council. Foam It Green has been recognized with a TerraPass for balancing their carbon footprint.

Wednesday, October 26, 2011

Home Builder Project

Harmon Builders recently completed a job for the Miller family that incorporated many energy saving features in the design. We were able to experience working with a variety of interesting 'green' products and achieve a beautifully designed space, inside and out. This was a very exciting project to be involved with as a home builder, as we discovered even more cutting edge materials and techniques. We hope to bring the advantages of passive solar heating and natural cooling strategies and our experience with different products to more clients.