Senior Project Manager with ConSol
John Morton is Senior Project Manager with ConSol where he works with homebuilders to train their staff and trade partners to build high performance walls and attics. He joins us this month to update us on the latest report on the energy calculations for the ABC Green Home 3.0
GHB: By what system is the ABC Green Home 3.0 being evaluated?
JM: We are using a metric known as Energy Design Rating (EDR). It is an alternate way to express the energy performance of a building using a scoring system where 100 represents the energy performance of the Residential Energy Services (RESNET) reference home characterization of the 2006 International Energy Conservation Code (IECC). A score of zero represents the energy performance of a building that combines high levels of energy efficiency with renewable generation to “zero out” its TDV energy. Because EDR includes consideration of components not regulated by Title 24, Part 6 (such as domestic appliances and consumer electronics), it is not used to show compliance with Part 6 but may instead be used by local jurisdictions pursuing local ordinances under Title 24, Part 11 (CALGreen).
GHB: What does the designation ‘Standard Design’ building signify?
JM: As a Standard Design building under the 2016 Building Energy Efficiency Standards is significantly more efficient than the baseline EDR building, the EDR of the Standard Design building is provided for Information. Similarly, the EDR score of the Proposed Design is provided separately from the EDR value of installed Photovoltaic(PV) so that the effects of efficiency and renewable energy can both be seen.
GHB: What are the most significant ‘take-away’s from the latest report?
JM: In the energy design rating, you can see the EDR of a Standard Design building is 46.6. The EDR of the Proposed Design for the ABC Green Home 3.0 is 47.2, obviously making it’s EDR higher than the Standard Design. However, with the EDR Value of the Proposed PV on the project at 47.9, the Final EDR of the Proposed Design comes out at -0.6, which is extremely efficient—the design produces more than it takes in.
GHB: What features of the home are the greatest contributors to that deficit?
JM: The attic insulation in the flat and rafter portions are both rated R-49 and the exterior wall insulations are R-23+R5/R-23. The interior garage walls were also rated R-23. The tighter the building envelope, the less heat-transference one way or the other, which leads to less heating or cooling which then means less energy expended. Energy efficiency starts in the insulation of walls and attics. But the PV is what “zero’s out” the home.
GHB: Is there anything additional to take special note of in the report?
JM: Space heating of the Proposed Design is at a 41.6 percent improvement over Standard and cooling is an 8.8 percent improvement on Standard. Water Heating was another major factor, with a 13.3 percent improvement on Standard Design.