Creates a Family Affair
By George Harvey
Tom Moore Builders has a new development in Vermont that stands out in more ways than one. The development’s three homes are all being built for members of a single family. The largest is being built for the parents, and the other two are for two married daughters, with a site reserved for a third daughter. These are high performance homes, and examples of energy efficient construction.
The family is close and its members are very excited about the fact they will be living so near each other. The land for their homes was purchased by the parents. The engineering for the property was done by Champlain Consulting Engineers and the site work is by Island Excavating.
All three homes are oriented toward views to the north, and this makes the high performance of the homes challenging. The large areas of glass face north when you would optimally design them to face south. All three have views of a Vermont valley, the town of Hinesburg, and Lake Champlain.
The two daughters’ homes are modular. People who are unfamiliar with modular construction might be tempted to think that means they are identical, but such is not the case. Though the underlying modular components are similar, the homes are custom-made, and not of the same design. Each has three bedrooms, but they are not the same size. One of these has a music studio, and the other has a third story finished attic. One is 2100, the other is 2560, square feet.
The modules were constructed by Preferred Building Systems (PBS), of Claremont, New Hampshire. Their modular construction provides a number of advantages. One limitation is that they need to be transportable. They need to be built and no wider than 13 foot 10 inch widths. They have the distinct advantage of being built in a plant, where the conditions are controlled. This means that they can be built to a higher standard than most construction done entirely in the field, and are unexposed to weather during manufacturing.
With site preparation completed, installation of the modular components of the buildings went very fast. It took about a day and a half for each set. Preferred Building has their own installation crew and crane, which assembled the modular sections, finished the roofs, and made the units water tight. At that point, Tom Moore Builders took over once more.
The homes were built to similar standards, and they are extremely energy efficient. The walls have six inches of dense pack cellulose. Three inches of EPS Silverboard has been put on the exterior. The foundation has three inches of Dow insulating board. The flat ceilings have 24 to 30 inches of loose cellulose, and the sloping ceilings have seven inches of closed cell spray foal. Windows are triple-pane models from Paradigm.
The larger of the two modular homes has a Bosch Greenstar 151 Combi gas boiler, with an efficiency rating of 95%, and hot water radiators. The smaller home has a York two-stage high efficiency gas furnace, with an efficiency rating of 96%, and a three-zone system. Each home has a 50-gallon double insulated electric hot water system, and each has a separate drilled well. Electrical work was done by CAE, headed by Corey Estus, a company that has done many projects with Tom Moore Builders.
With the daughters’ homes largely completed in September, and one family already moved in, construction started on the parents’ home. Foundation digging started in September. This home is to be panelized and erected at the site, with performance standards even higher than those of the modular structures. Because it is being built entirely at the site, the process will take longer.
This home was not a candidate for modular because the sections are wider than 13 feet 10 inches. The foundation will be a VTICF-supplied Amvic ICF foundation with an R-value of 30. The walls will be framed with double two-by-fours constructed 12 inches on center with 12 inch dense-pack cellulose insulation having R-43 value. The windows will be European tilt and turn and triple pane, with very high insulation values.
Electric power for the homes is provided by a solar array on the site. With three homes drawing power from the array, each having its own electric meter, the project’s power is group-net-metered. Dave Bonta, who founded the USA Solar Stores, worked on the project personally, with the Sherwin Solar Store in Essex Junction, Vermont.
The array has sixty Astronergy modules of 255 watts each, for a total capacity of 15.25 kilowatts. The system has three Kaco Blue Planet transformerless inverters. The solar array is mounted on DP&W racking, which can be adjusted seasonally. The seasonal adjustment provides up to 20% more energy than a fixed mount of the same capacity, but is nowhere near as expensive or complicated as solar trackers. Electrical work and installation of modules and inverters were done by Sherwin Solar Store.