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As California moves toward all-electric buildings, heat pump water heaters (HPWH’s) are becoming more popular because they are so efficient and don’t use natural gas.
In this 2-minute video, we've partnered with 3C-REN to provide a quick overview of HPWH’s and the parts and pieces of installation.
In the low-hanging-fruit category of energy performance, correctly specifying and installing insulation is near the top of the list. Still, we frequently see insulation thickness that is not in alignment with the size of the wall cavity or an installation that doesn’t fit tightly. Two big issues to address, both in the construction documents and in the field, are compression and gaps.
Compression reduces R-values
Compression can occur when the thickness of insulation required for the R-value is too large for the size of the studs. Not uncommon, the inconsistency could stem from a change of wall thickness due to plumbing conflicts, structural analysis, product availability, Title 24 requirements, etc. The impacts, though, are significant. For example, R-19 batt insulation that is 5.5” thick fully ‘lofted’ would fit in a nominal 2x6 cavity. Shove that same insulation into a 2x4 wall, and the effective R-value drops to R-12! Compression also occurs when insulation is pushed behind a pipe or conduit instead of cut around it, or when a framing bay is narrower than a nominal 16” space and the installer doesn’t cut the width of the batt.
Gaps could allow convection and condensation
Properly installed wall insulation has contact to all 6 surfaces of the stud cavity: at the header and footer, at the stud on either side, to the outside wall and to the inside wall. We put emphasis on this last surface because we often see insulation that is pushed into the cavity so much that when the sheetrock is installed there could be an inch or more gap between the insulation and the sixth surface. Be sure that batt insulation fully touches the outside wall and is fully lofted to the interior. If there is vertical airgap, convection could occur within the wall cavity, which tremendously reduces the effective R-value.
Gaps can also occur at the top of the cavity, either if insulation isn’t installed correctly or if it slumps over time. The gap at the top of a cavity is concerning as moist interior air could come into contact with a cold exterior wall, causing condensation. Condensation, of course, could lead to mold growth and health concerns.
Tips for getting the best fit
Interested in getting the best performance from your insulation? Here are few tips to consider:
· Include a Quality Insulation Installation (QII) HERS verification as part of your project. QII applies to residential and non-residential projects, as well as new construction or alterations and covers air sealing as well as insulation.
· Don’t just leave it to the Title 24 report - add notes to your construction drawing indicating expectations for a QII-level of installation.
· Whether you are the owner, architect or builder, require a meeting with the insulation subcontractor prior to the start of work and communicate expectations at that time. Trouble-shoot difficult areas and discuss the company’s own quality-control process and employee training program.
· Consider using a blown-in cellulose or similar product that fills the cavity more easily.
Looking for more information about appropriate insulation implementation? Check out the Quality Insulation Installation (QII) Handbook, developed by CalCERTS, Questions on energy performance or Title 24 energy compliance? Reach out.
Would you like to see inside an all-electric, Zero Net Energy commercial building, right here on the Central Coast? In this 3-minute video we walk through People’s Self-Help Housing’s new 24,000 SF headquarters located in San Luis Obispo. In the video we highlight the heat pump systems for heating, cooling and hot water, take in a roof-top view of the 115 kW photovoltaic array, and wrap up with lighting and all-electric appliances. Enjoy!
We’re pleased to continue offering in-person and online classes through 3C-REN. Here are a few of the upcoming courses:
ENERGY CODE COMPLIANCE: USING HERS MEASURES (PART 2)
Wednesday, March 20th @ 9:30 am – 11:00 am
Elevate the efficiency of your projects with our HERS Integration Series! Join us for Part 2, featuring Jennifer Rennick from In Balance Green Consulting and Paul Dunn from Central Coast Energy Compliance. This session will delve into HVAC and indoor air quality. Learn essential integration strategies and HERS measures tailored for architects and builders. REGISTER
Missed Part 1? Check it out at the 3C-REN On-Demand library.
DETAILING FOR HIGH PERFORMANCE ROOFS AND WALLS
Thursday, March 21 @ 10:00 am - 11:00 am
We know the concepts behind providing a great building envelope – air tight and well-insulated– but how, exactly, do we do that? In this course, we’ll provide ‘sketch-level’ details of high-performance wall and roof assemblies that designers and builders can use as an outline to develop their own project-specific details. REGISTER
ENERGY CODE IMPLEMENTATION SERIES
Accessory Dwelling Units (ADUs) - REGISTER
Wednesday, May 8 @ 9:30 am - 11:00 am
Since the energy code update took effect in January 2023, the industry is adjusting to design, detailing and construction to meet compliance. In this series, we’ll review the code requirements with a focus on what to include in construction documents to streamline the permitting process and tips for construction to ease signoffs and occupancy.
Past courses in the series (available on demand soon)
Energy Code Implementation: Single Family New Construction
Energy Code Implementation: Single Family Additions and Alterations
Future offerings
Energy Code Implementation: Multi-Family (June 12)
Energy Code Implementation: Non-Residential (TBD August)
