Score LEED® Points With CHP
When designing a new building, one of the most important choices is its energy system. The design team’s choices are crucial to the building’s performance and are key factors in its economic and environmental impacts. The energy system can also be designed to provide a reliable electricity supply in the event of long-term grid interruptions. And for building owners seeking U.S. Green Building Council LEED® green building program certification, measures to reduce energy cost and consumption will significantly improve the LEED score a building will achieve.
Combined heat and power (CHP), also known as cogeneration, has a long record of providing buildings with reliable electricity, steam, and hot water with lower costs and emissions than grid-supplied electricity and an on-site boiler. And, because of its superior energy efficiency and lower energy costs, CHP can earn buildings seeking LEED certification significant LEED points.
What is CHP?
CHP is an integrated system of power production that harvests the heat generated during the production of electricity and utilizes that heat, which would otherwise be wasted, to efficiently produce steam or hot water.
With CHP, buildings can:
- Lower energy costs. CHP can reduce energy bills due to its high efficiency and can provide a hedge against energy cost fluctuations.
- Reduce air emissions. Because less fuel is burned to produce each unit of output, CHP reduces emissions of greenhouse gases and other air pollutants.
- Ensure a reliable electricity supply. CHP can be designed to maintain a building’s electricity supply during blackouts and other interruptions.
CHP can be a good fit for a wide variety of commercial and institutional facilities including office buildings, apartment buildings, hotels, nursing homes, hospitals, and schools. Moreover, installing and managing CHP systems has been simplified by arrangements where third parties install, own, and operate the CHP equipment; and by modular CHP units, which include all of the CHP components (e.g., engine, generator, and heat recovery equipment) packaged together.
Taking Efficiency to a New Level
So where in the LEED scoring system can design teams capitalize on CHP use? Of the 40 points required for the current LEED v4 certification, CHP can help buildings earn up to 18 points in the “Optimize Energy Performance” credit.
To achieve the maximum number of LEED points under the “Optimize Energy Performance” credit, design teams must run a whole-building energy simulation to demonstrate the energy savings their “design building” has over a “baseline building,” as prescribed by ASHRAE 90.1 2010. Energy savings are measured on a cost basis rather than on an energy-unit (i.e., Btu) basis.
To account for CHP in the required energy model, the U.S. Green Building Council has developed a Methodology for Modeling Combined Heat & Power for EAp2/c1 in LEED® 2009[i]. According to this guidance, when determining total energy cost savings, a design building that uses CHP needs to account only for the cost of the fuel for the CHP system and any remaining purchased electricity, steam, or hot water the building uses. The electricity, steam, and hot water generated by the CHP system and used in the building do not need to be accounted for in the cost savings calculation.
CHP: Real-World Results
A number of building design teams are already using CHP to increase their buildings’ respective LEED scores.
- The owners of “315 on A,” a 255,000 square foot apartment building, chose CHP to meet their goal of delivering reliable, low-cost electricity and heat to the building’s residents. The building utilizes a 75 kW Aegis Energy modular CHP unit to provide electricity, domestic hot water heating and space heating. Completed in 2013, the building is certified LEED Gold® under LEED v2009. The CHP system earned the building four points under the “Optimize Energy Performance” credit.
- This CHP system was installed by Aegis Energy Services under a shared savings agreement, which means no up-front cost to the building owner. The building owner pays a discounted rate for the electricity used and pays market rates for the heat provided by the CHP; and Aegis pays for the natural gas that runs the CHP. Part of the owner’s motivation for the CHP system was its inherent operating cost efficiency. “In a market like Boston, where gas heating is treated as a building operating cost and not prorated back to the residents as part of their utility bill, co-generation is a win-win for owners,” said Renee Loveland, Manager at Gerding Edlen, the “315 on A” developer.
- After Hurricane Sandy, reliable electricity supplies for residences are more important than ever. Completed in summer 2015, Macedonia Apartments in Flushing, New York utilizes a 200 kW CHP system consisting of two Tecogen InVerde 100 kW modular units to ensure that the lights stay on in the event of another grid outage. The CHP system provides electricity for the building, and heat recovered from the system is used for space heating, domestic hot water, and to power the building’s absorption chillers. The building earned Gold certification under LEED in 2009, with the CHP system contributing 16 points under the “Optimize Energy Performance” credit. The CHP system also saves the building more than $200,000 in annual energy costs.
- A Whole Foods Market in Brooklyn, New York earned Platinum certification under LEED v2009, and its CHP system helped the store meet its goal. Powered by a 157 kW Caterpillar reciprocating engine/generator, the system provides electricity, heating, and cooling and can support continued store operations in the event of a grid outage. The store earned all 19 “Optimize Energy Performance” points.
Learn More about CHP and LEED
The EPA CHP Partnership has developed a fact sheet for architects and engineers that introduces CHP and its benefits and summarizes how CHP is treated under the LEED for Building Design and Construction: New Construction and Major Renovations rating system. Another fact sheet that describes how buildings connected to a CHP-equipped district energy system (DES) can earn more LEED points than they could otherwise receive is also available.
The Partnership has also developed the LEED® CHP Calculator, an Excel-based tool that estimates the energy cost savings and “Optimize Energy Performance” points a building with CHP can achieve.
EPA’s CHP Partnership website also contains a wealth of information to help buildings implement CHP.
Gary McNeil is the Communications Director for U.S. EPA’s Combined Heat and Power Partnership. He holds a BA in Economics and a Master’s in Business Administration from the University of Washington.
Charlie Goff is a Sr. Energy Consultant with Eastern Research Group, Inc. (ERG). He holds a BA in Mechanical Engineering from Washington University in St. Louis, and a MPP from Georgetown University.
[i] The methodology presented in this document also applies to LEED® v4.