Efficient gas boiler provides heat and backup hot water
Solar collector on the roof provides hot water
Rooftop solar collector faces south
A Row House Reduces its Carbon Footprint
A 1910 row house in Old Town Alexandria had been updated in 1990 with insulated windows, a new mechanical system, and attic insulation. But the house remained uncomfortably hot upstairs in the summertime. Additionally, the flat roof had chronic leaks. When the air conditioning went out in the summer of 2007, the owners decided to tackle an integrated, whole-house, energy upgrade.
We added 3” of tapered, rigid insulation to the top of their roof deck. This created a greater slope for roof drainage. Because this R-20 insulation was added to the top of the roof, all of the existing attic mechanical equipment is now running through conditioned space. We also replaced their black rubber roof with a white, TPO membrane roof. The white roof reflects the sun’s heat, reducing heat gain in the summer.
We upgraded their mechanical system as well. We replaced their SEER 10 air conditioning system with a SEER 15 system. We replaced their 15-year-old forced-air furnace with a 96% energy efficient boiler. We sealed all accessible duct runs in the attic, basement and crawl space with mastic.
As the final part of this upgrade, we added a solar hot water system. Evacuated tubes, which can heat water to 180 degrees, sit on the roof. They feed into a well-insulated hot water storage tank. On cloudy days, the boiler provides back up.
Energy bills for the summer of 2007 were about 65% of the previous year’s bills. The solar hot water system is projected to provide three-quarters of their hot water. Best of all, the clients report that the second floor of their home is comfortable, with no difference in temperature between floors. Stay tuned to hear about the winter conditions…