Cost- and Energy-Efficient Attic Designs for California Homes
New attic designs that mimic ducts in the conditioned space have the potential to reduce energy in homes at costs competitive to existing practices.
The recipient instrumented three existing homes in the City of Rio Vista with the following attic approaches: Vented with R-38 on the ceiling, Sealed with box netted R-38 under roof deck, and vented with R-38 on the ceiling and R-19 under roof deck. The monitoring started in August 2018. Unfortunately, the grant expired on June 30, 2018. The Energy Commission staff and the recipient are exploring options for obtaining the monitored data and results for the homes and concluding the project.
This project evaluates, tests and refines two different attic designs in California homes, and recommends the best approaches to home builders addressing cost-effectiveness and energy-efficiency. The baseline will be the current energy efficiency code practices for ventilated roof attics with no additional attic insulation and ducts within the attic that comply with the current energy code (2013) requirements for ducting.
The project could lower energy cost to ratepayers by developing attic assemblies that allow ducts to perform as if they were located in the "conditioned space" and reduce HVAC energy costs without adding cost to builders. Pilot work on the attic designs have demonstrated that these approaches can potentially be cost neutral to ratepayers. Assuming a market penetration of 73% of the current single-family market, new construction with these designs could potentially recoup the costs to ratepayers within a single year.
Key Project Members
Electric Power Research Institute, Inc.
Oak Ridge National Laboratory
Oak Ridge Associated Universities
Michael L Dalton, CPA