The idea for this guide came after repeated experience while doing energy modeling for LEED: most projects I worked on (even high-profile ones that looked good on paper) unnecessarily missed the opportunity for 4-12, or sometimes even more LEED energy points.  

This could have been prevented in two ways:

1. The best solution is to involve the energy modeler/consultant from the beginning of design so that energy analysis can be used as a guide for design. This approach allows projects to precisely know the cost vs. LEED benefit of different energy options and achieve the most points for what the project wants to spend.  However, on most projects my involvement would start after most energy design decisions were already made, so it was impossible for me to consult on options that performed better in LEED. 

2. In these common cases where projects only use energy analysis to calculate energy performance after design, engineers involved in energy design can still prevent losing LEED points if they follow certain, easy energy design guidelines, based on the LEED rules. Energy consultants/modelers that analyze projects for LEED usually know them, whereas engineers often do not, which is a recipe for lost opportunity for projects with this approach.

I sincerely hope that you’ll and your teams will utilize this knowledge to make decisions in energy design that will increase your projects’ LEED achievement.

I will also provide references to LEED documents and energy code, ASHRAE 90.1 to easily find the source for each of these guidelines.

I will also share with you a segment on energy design guidelines for LEED 4.1.  This standard can optionally be adopted for the energy model credits now, but will be required at some point in the future.  These new guidelines are important because LEED 4.1 has different rules for earning energy design points and projects may not meet minimum requirements or earn sufficient energy points for their LEED goals.  

Guideline #1 for HVAC System Selection (LEED V4) (4-10+ Additional LEED Points)

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This first guideline is both the simplest and the most impactful:

• For non-residential buildings that are more than 3 storeys OR more than 25,000 square feet, using electric heat pumps for heating will earn 4-10+ more LEED points than using gas heating.  

• For air source heat pumps, expect 4-6 additional points over gas heating. For geothermal heat pumps, the range is 6-10 additional points.

The reason that heat pumps generate so many more LEED points than gas heating for larger non-residential buildings is that the LEED v4 rules state that these heat pumps are compared to electric resistance heating in the baseline model of the building in LEED 4.0. (the proposed model is the building with the actual energy design and that gets compared to a minimum energy design to code, called the baseline model)

"If you think this sounds like massive loophole, you are right."

If you think this sounds like a massive loophole, you are right.  This is because electric resistance systems for heating are rarely used on large buildings because of the high cost, and the difference in energy use between these and heat pump systems is huge (up to 85% savings) in comparison to the energy use between an “average” baseline gas system and a proposed gas system (about 16% savings). Both gas and heat pump systems are much more cost efficient and greenhouse gas reducing than electrical resistance systems, yet heat pump systems get rewarded disproportionately, based on this LEED rule.

It is important to note that this guideline only applies to systems that use only electricity for heating. A gas/electric hybrid system will be considered that same as gas in LEED and ASHRAE rules.

LEED and ASHRAE figured this out because they completely changed the rules for creating the baseline building for HVAC in LEED 4.1.   But until LEED 4.1 becomes mandatory, this simple guideline will remain the single biggest factor in getting more LEED points for larger, non-residential projects. 

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Which System Types are Compatible with this Guideline?

Common system types that work with this guideline:

• Mini-Split Heat Pumps, Packaged Heat Pumps, and Large VRF Heat Pump Systems. Expect around 4-6 additional points with these systems. One consideration is that some engineers have reported difficulty in long term maintenance and reliability with large VRF Systems.

• Geothermal Heat Pump Systems. Expect around 6-10 additional points with these systems. These systems are very efficient and are considered very reliable. The only downside is the initial installation cost.

• Water Source Heat Pumps with Rooftop Heat Pump or Electric Boiler.  Typically, these systems would use a gas boiler heat the water loop, but this would disqualify the system from compliance with this guideline because it is a gas/electric hybrid.  However, one solution would be to use air to water rooftop heat pump to heat and cool the building water loop.

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Small or Residential Projects?

But what about residential projects or non-residential projects that are 3 storeys or less OR are smaller than 25,000 square feet?  Is it best to go with electric or gas heating for these projects?

This answer is much more complex, and I will cover it in more detail in a future section on gas versus electric in residential or small commercial projects.                                                                      

But here is a rough guideline:

• Efficient air-source heat pumps or efficient gas-fired heating will generally receive about 1-2 LEED points.

• Geothermal heat pumps typically earn 2-4 LEED points, but may not be worth the additional up-front cost.

In the next section, I will talk about one of the most impactful and least understood factors in the LEED Energy Model: process loads (plug-in and permanently installed equipment)

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Link to LEED Documentation

If you would like to see the original source of this information, here is a downloadable excerpt from ASHRAE 90.1 2010 which shows how the baseline systems are selected.

Click the image below to view: