Dwellgreen uses a six-step process to create a sequenced action list for home improvements. It consists of gathering data, interpreting the data, deciding what might be changed, deciding whether to go ahead with the changes, and monitoring the effectiveness of any changes.
The sad case of a “rainy”attic will illustrate this process:
Step #1 WHAT ARE THE CURRENT CONDITIONS? A homeowner reports a problem of water dripping from their attic down through their walls. The inspection team observes water dripping from the rafters, in dry sunny weather. Further inspection reveals that the attic air-conditioning (ac) ducts are improperly installed and leaking lots of 50oF air. The dewpoint of the 90oF outside air was determined to be 70 oF; if the outside air were cooled to 70 oF, its moisture would start to condense. The attic has foam insulation between the rafters but is not sealed. The attic two eave vents to ventilate the attic.
Step#2 ARE THE CONDITIONS GOOD OR BAD? The inspection team determined that the 50oF air, escaping from the ac ducts, was cooling the 90oF humid air from the eave vents creating internal “rain.” The ac air had cooled the outside air below its 70oF dewpoint. This was like cold Canadian air dancing with warm Gulf Coast over Kansas air to form violent rainstorm and tornadoes. On the positive side, the foam insulation between the rafters was a benefit in keep the home cool.
Step #3 WHAT MIGHT BE CHANGED? Seal the eave vents. Repair and seal the ac ducts. Service the air conditioner to make sure that it is effectively dehumidifying the air.
Step #4 WOULD THESE CHANGES MAKE THE CONDTIONS BETTER? These improvements would reduce the energy requirements for cooling and dehumidification. Sealing the attic eave vents and ac ducts would stop the internal “rain” by preventing hot outside air from mixing with cool ac duct air. The sealed attic eave vent,s in conjunction with the existing foam rafter insulation, would create a sealed attic which often cuts air-conditioning bills by 25%.
Step #5 SHOULD THESE CHANGES BE IMPLEMENTED? The homeowner and inspection team decided to implemente all the changes suggested in STEP # 3. This was an emergency situation and the fixes were relatively cheap.
Step #6 MONITOR THE RESULTS. Don’t worry –this story had a happy ending! After the improvements were implemented, the inspectors placed an automatic humidity recorder in the house. The recorder showed a slow but steady drop in interior humidity from a high 60% to a normal 40%. The rain in the attic became a drought. The subsequent annual electric utility bills showed a 15% drop due to lower cooling and dehumidification loads. The success of this intervention provides confidence in fixing similar problems in the future.
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