LEED v5: Focus on Decarbonization

It’s coming… USGBC is preparing to launch the next iteration – v5 – of its rating system in the next year. This new version represents a significant shift in how the system is conceptualized, with some impacts on point distribution. Broadly speaking, LEED is utilizing three impact categories as an organizing framework:

·      Decarbonization (50%)

·      Quality of Life (25%)

·      Ecological Conservation & Restoration (25%)

Proposed LEED v5 checklist

These impact categories are distributed across existing credit categories and will apply to all rating systems. So what does this mean for LEED projects in the future? And how does California’s emphasis on decarbonization and electrification align with LEED’s priorities?

USGBC’s overarching goal for LEED v5 is to “drive the industry toward a decarbonized built environment across all major sources of emissions: operational, embodied and transportation.” This requires carbon literacy among practitioners regarding both sources of emissions and reduction opportunities.

In that vein, they are taking guidance from the adage “You can’t manage what you don’t measure” and introducing new prerequisites that aim to build a project team’s carbon awareness. They are:

LEED v5 credits addressing decarbonization goals and strategies

  • Carbon Assessment (Integrative Process)

  • Operational Carbon Projection and Decarbonization Plan ( Energy & Atmosphere)

  • Assess Embodied Carbon and Planning for Zero Waste Operations (Materials & Resources)



There are also new credits available for projects that achieve carbon reductions via “Electrification” (5 pts) and “Reducing Embodied Carbon” (8 pts). These credits support California code updates that reward – and in some cases require – new residential projects to incorporate heat pumps for space conditioning and water heating and solar panels as an electricity source.

An often overlooked source of greenhouse gas emissions is refrigerants. An update to the Fundamental Refrigerant Management prerequisite limits projects to refrigerants with low global warming potential (defined as <700), effectively prohibiting the use of common refrigerants like R410a and R134a, which have GWPs of 2088 and 1034 respectively.

Beyond these building-based direct impacts on U.S. carbon emissions, the updated rating system is also addressing indirect impacts of the building sector through enhanced credits in the Location and Transportation category (now worth 15 pts) and with a new prerequisite called “Planning for Zero Waste Operations.”

This is a lot. And while these changes are yet to be finalized, the ultimate goal is to empower project teams to leverage the many ways our work impacts carbon and other greenhouse gas emissions. Have a project targeting low or zero carbon? Reach out!

Right-sizing Insulation for the Wall Cavity

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.

Quick Video Tour of a Local All-Electric ZNE Office

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!