Photo courtesy of UpDwell Homes
With the continually increasing requirements for Title 24 Energy Code, VCA has noticed the intent and purpose of meeting Home Energy Rating System (HERS) third-party testing can be difficult for some installers and designers to understand. Typically, the energy model will instruct owners and installers which HERS tests are required. If an energy model is not available, prescriptive requirements will trigger specific tests for specific installation types. The tests are for quality assurance for equipment installation and performance.
Indoor Air Quality
Indoor air quality is primarily a concern for tenant health. This test ensures a unit is properly ventilated to meet the minimum requirements outlined by ASHRAE 62.2. The intent is to confirm a dwelling unit achieves a minimum exchange rate of fresh air into the dwelling unit so contaminants such as CO2, CO, or other volatile substances do not accumulate. Additionally, the test ensures the unit isn’t over ventilated. Over ventilation uses unnecessary power to run the exhaust or supply fans at higher-than-necessary speed and will also increase the load on HVAC systems. VCA also verifies that all air coming from powered outside air fans is filtered before entering the space to prevent contaminants from outside. Overall, this HERS measure aims to provide proper air quality and run efficiently.
Kitchen Range Hood
Kitchen range hood testing, also related to indoor air quality, currently requires that units feature HVI-certified range hoods that meet 100 cubic feet per minute minimum air flow to the outside. The intent is to make sure smells, volatile oils from cooking, smoke, and other cooking by-products are not left to sit in the space and accumulate on building materials and surfaces, such as the ceiling, or in occupants’ lungs. This verification reduces air contamination, extends the life of HVAC units’ air filters, protects occupant health, and reduces moisture build up in materials such as drywall or cabinet materials, increasing building durability.
Fan-Watt Draw and Airflow
Fan-watt draw and airflow testing primarily tackles energy efficiency and mechanical system durability. This test verifies the energy consumption of a dwelling unit HVAC fan is less than or matches the state-allowed maximum. The testing also ensures the fan’s airflow is high enough to provide full efficiency of temperature transfer in the fan coil unit. Low efficiency of temperature transfer prevents a fan coil from operating at its full potential and may also reduce the effective life of the equipment due to increased condensation, fan coil icing, and compressor refrigerant issues. Preventing moisture build-up will help maintain the building’s aesthetic and structural lifetime.
Quality Insulation Installation
Quality insulation installation (QII) is a measure many projects try to avoid, but it is one of the most easily implemented and typically doesn’t impact a project’s budget as much as anticipated. QII benefits include energy savings, decreased moisture transfer, increased mold resistance, better sound attenuation between units, and increased fire resilience due to reduced thermal transfer. QII requirements are very meticulous because reduction or missing insulation of only a small portion of the envelope decreases the performance of that assembly in a logarithmic fashion. Many insulation batts tend to “slump” in their stud bays or cavities over time, which QII practices mitigate. QII is well worth the effort and marginal extra cost when considering insulation protects the structure and provides multiple other benefits.
Envelope Leakage/Blower Door
Reduced envelope leakage/blower door testing is a test of how much air is transferred over the envelope of a dwelling at 50 Pascals of pressure (roughly equivalent to a 30 mile per hour wind from outside). This test is to ensure no excessive outside air enters the unit. More energy is wasted if the conditioned air from inside is leaking through cracks in the envelope. There’s also the consideration for outside contaminant air intrusion becomes a health concern. Tenant complaints from smells transferred across adjacent units reduce as a result of the measure as well, as tenants don’t want to smell their neighbor’s meal every time they cook next door.
Duct Leakage
Duct leakage tests aim to save energy, make sure air delivered to occupants is healthy, and to verify quality of installation. A well-built duct system saves energy by making sure the BTUs spent on conditioning that space aren’t wasted on cooling down interstitial wall or soffit space. Additionally, poorly sealed ductwork has a higher risk of contaminants within the interstitial building cavities to enter the system. Tenants will greatly appreciate the fact that their ducts are installed well, and their air is adequately filtered with MERV-13 grade filtration.
While every HERS testing measure may not pertain to your particular project, the tests provide many benefits. Applying these measures can increase dwelling durability, increase energy performance, reduce operating costs, and provide greater tenant comfort. The measures pay for themselves in the long run, and we can be satisfied in producing quality, tested homes providing for a sustainable future.
Contributing writer: Chris Halamandaris
Moe Fakih, Principal
mfakih@vca-green.com
Robyn Vettraino, Principal
rvettraino@vca-green.com