TECHNICAL SUMMARY
This is the overall summary from Get Green Remodel www.get-greenremodeling.com (858.217.5800)
We found, like in most homes built prior to current building codes, that attic insulation, duct leakage, and air leakage are common issues in the homes we audited.
Insulation is important no matter what climate zone you are in. Wall insulation is just as important as attic. In fact, wall insulation that is dense packed provides two benefits: a high R-value and air sealing. By dense packing, we can get insulation into all the cracks and crevices and seal all the small air leakage areas. Two of the homes we assessed had installed an additional layer of insulation on top of existing fiberglass batts. However this still did not bring them within the recommended R-value of 38 for our climate zone. The two homes that had no added insulation had an average effective R-value of 4, well below the climate zone recommendation. We recommend installing blown-in cellulose; environmentally conscious, quick application, high R-value, and even distribution are just some of the benefits.
On average, homes with HVAC ducting, have a leakage factor of 30%. From the four homes we assessed, an average leakage factor of nearly 35% existed. Leaky ducts can lead to discomfort as well as health/safety concerns in many homes. Duct leakage results in reduced air flow and inconsistent temperatures at registers. Home occupants must adjust the thermostat higher or lower to compensate for this loss. Ducts are most leakiest around trunk and branch connections and at the air handler supply and return plenums, as well as register boots. The best solution for air sealing ducts is by a product called mastic. A flexible sealant that varies in consistency from that of mashed potatoes to yogurt. Because it never fully hardens, mastic stretches as the duct (or other surface) expands and contracts, and can withstand moisture. In 3 of the homes, we found that a wall cavity was used as a return for the HVAC system. While the wall cavity may be a convenient spot for a return, this can lead to poor indoor air quality and HVAC in-efficiencies. In this case, we recommended installing a dedicated sealed return duct. We found in some of the Del Cerro homes that HVAC systems were oversized by 30-50%. This can prevent a HVAC system from reaching its Steady State Efficiency causing the system to cycle on more times than necessary and greatly reducing the efficiency.
Air sealing is the most important home energy upgrade. It affects the comfort, health, safety and energy efficiency of home. For the homes we assessed, they averaged nearly double the recommended Building Air Standard, a guideline set by the Building Performance Institute. Most air leakage occurs from the attic or crawlspace where wiring and plumbing penetrations enter the conditioned space. Dropped ceilings, open wall cavities, and recessed lighting are also common leakage areas. Solutions include using caulking and expanding foam for smaller cracks and openings, and installing drywall for larger openings like dropped ceilings. ICAT (Insulation Contact Air Tight) recessed fixtures are a great product when replacing can lights. They are able to prevent significant leakage and tolerate insulation around the unit without presenting a fire hazard.
The Assessment
The assessment is the most important part of reducing energy use and making your home more comfortable and healthier. In some cases we can generalize certain home features in particular neighborhoods, like whether they have crawlspaces, attics, cathedral ceilings, etc, that may have been common for the builder at the time. But getting inside and speaking with the resident gives us information about behavior and any special concerns the homeowner may have. The assessment gives us a chance to explain the science behind building performance and how modeling our recommendations, can give the homeowner energy savings and improve health/safety, and comfort. We can build trust with the homeowner, allowing them to walk around with us, pointing out areas of concern that they may have never recognized. In a sense we are making them aware of things they have never seen before, and helping them understand that even though they can't see it, does not mean its not affecting them
Savings
Savings can vary greatly from home to home depending on the amount of people living there and their behaviors. For the Del Cerro samples, we found with homes averages $180 utility bills, we could potentially save them 15-30% off their utility bill. Because we reduce their energy consumption with home performance upgrades, we can now install a smaller or right-sized system specific for their needs. Saving them thousands if not tens of thousands off of a solar system installed without building performance upgrades. This enables us to install solar on homes that may not have had the available roof area for a larger system
Assess. Improve. Solar. This is our philosophy and we know that homeowners will get the most value out of energy efficiency, health/safety, and comfort when they combine home performance improvements with solar.
