Converting a shed to a home office in Santa Fe, N.M., took time, research and planning, but was worth the effort. By investigating products and working closely with the contractor, the 700-square-foot (65-m2) home office now is in business.
Because temperature swings are common in New Mexico, a basement was excavated below the shed to help regulate temperatures year round. Using the Earth’s constant temperature of around 55 F (31 C) and moving air from the warm parts of the shed to the cool sections in the winter and vice versa in the summer, the need for an HVAC unit was avoided. The basement walls are concrete block and covered with 1 inch (25 mm) of insulation board for an estimated R-value of 14 to 16. An addition with adobe walls was built onto the existing 300-square-foot (28-m2), 50-year-old adobe shed. Because adobe has no rated R value, the interior of the adobe walls was covered with 4 inches (102 mm) of spray-polyurethane insulation, resulting in an estimated R-value of 24. With the adobe, insulation, rough coat and natural stucco finish, the walls are nearly 1-foot (0.3-m) thick. The 6 inches (152 mm) of spray-polyurethane foam on the roof has an R-value of 36. The spray foam is covered with stucco and keeps the office cool in the summer and warm in the winter.
Double-pane, low-E windows and skylights are fitted with automated controls to open when the interior temperature rises; they close in cold temperatures and when it rains. Open windows and skylights work with ceiling fans to create cross ventilation.
Heating is accomplished primarily through the solar-thermal system installed on the roof. The solar panels are tied to radiant-floor heating installed in the concrete basement floor; the heat rises naturally, warming the entire shed. The panels also provide hot water to the office and auxiliary heat for the main house. About 100 F (56 C) water is furnished to the main house’s boiler, saving heating energy. A fireplace, capable of generating up to 26,700 Btu per hour, provides secondary heat to both floors of the office.
The office’s bathroom features cabinets made of locally milled wood, a low-flow showerhead and dual-flush toilet. To further save water, while excavating the basement, a 1,600-gallon (6056-L) below-ground polypropylene cistern was installed. All downspouts from the shed and house are piped underground to the tank. The system is capable of capturing more than 18,000 gallons (68130 L) of rainwater per year, which currently is used for irrigation.
The office complements the main house aesthetically while maintaining a low carbon footprint. With the solar-thermal system tied to the main house; a rainwater-catchment system; and low-energy features, like LED lighting in almost all fixtures, the office has not added to utility bills.
Doug Pushard is the founder and co-editor of HarvestH2O.com, a Web site that connects the public to written information about rainwater catchment. He can be reached at firstname.lastname@example.org or (505) 984-8907.