Leadership in Energy & Environmental Design
LEED Certification is a crucial standard by which the quality of commercial and residential properties are judged. Achieving an exemplary LEED score is representative of both efficient and environmentally conscious building design, and can be used to create a more marketable and client friendly commodity. LEED certified buildings impart less of a burden on the environment due to informed design choices which incorporate sustainable materials and efficient technologies. Through thoughtful and environmentally conscious construction, LEED certified buildings save costs in the long run and provide livable spaces that are healthy for both residents and the environment.
Knowledge of cogeneration technologies is critical for property owners who value the merits of LEED and ENERGY STAR certification systems.
On-Site cogeneration is recognized under LEED 2009 and LEED v4. The most applicable areas in which cogeneration may contribute to a property’s LEED score are the Minimum Energy Prerequisite and the Optimize Energy Performance credit. By qualifying for all of the available Optimize Energy credits, cogeneration technology alone could account for up to 45% of necessary LEED points to achieve the baseline certification. Combined heat and power technology could be applied towards multiple types of LEED credit, including:
Optimize Energy Performance
OnSite Renewable Energy (v2009)
Renewable Energy Production (v4)
Enhanced Refrigerant Management
The compliance pathway for the Minimum Energy Performance prerequisite that is most applicable to combined heat and power is the Whole Building Energy Simulation, which is a performance-based evaluation. Under LEED v4, savings of 5% for new buildings, 3% for major renovations, or 2% for core/shell renovations must be demonstrated as compared to the requirements of ASHRAE 90.12010 baseline building standards. Simulated energy savings are based on energy costs determined by developing energy models for the Design and Baseline buildings.
The USGBC details specific methods for modeling combined heat and power in LEED certification and how to award points:
- The primary method compares the costs of purchased grid electricity and purchased fuel used towards thermal generation between both the Design and Baseline Buildings.
- Optimize Energy Performance points are calculated based on the percent reduction in energy cost for the Design buildings as compared to the ASHRAE 90.12010 baseline building.
Below is a table containing the LEED points to be awarded for different percentage improvements over the baseline score due to implementation of cogeneration technology. (Source: EPA CHP Partnership)
As seen in the chart above, implementation of cogeneration equipment which results in significant improvements over the baseline level of energy consumption can account for a multitude LEED points.
In the figure below, a sample performance analysis of two commercial buildings in New York City and San Francisco illustrates the process in which LEED points can be awarded to buildings implementing cogeneration.
As described above, the overall combined heat and power point impact is based on a percentage improvement of energy costs over the baseline building. In this case, the prices of electricity and natural gas played an important role in the overall cogeneration point impact and resulted in the Hotel in San Francisco achieving more points that the Office Building in New York.
There are a few important factors to note regarding the usage of cogeneration in LEED certification.
- The cost-basis approach to determining the percent improvement over baseline does not fully underscore the environmental benefits of implementing cogeneration technology. Apart from savings on electricity and fuel, cogeneration provides additional environmental benefits in the form of less overall emissions per unit of energy created and drastically increased efficiency.
- The percentage savings requirements calculated under the Whole Building Energy Simulation methodology are based on the costs of energy rather than actual usage. Thus, the value of combined heat and power when expressed as LEED points is highly dependent on regional energy and fuel costs.
- Projects which retain all outputs from a combined heat and power system achieve more favorable cost-saving percentages than those which export a portion of energy outside of the bounds of a local system
WinWerks’ profound industry experience of construction standards and cogeneration allows clients to achieve considerable reductions in wasted energy and bolster their standing as environmentally conscious entities. Through the LEED certification methods described above, property owners who implement cogeneration will be left with not only an efficient, sustainable, and reliable source of energy, but also a marketable symbol of their commitment to the future of our planet.
Note on Living Building Challenge: The Living Building Challenge, which was developed by the International Living Future Institute, is a newer and more stringent set of guidelines focused on the construction and life cycle of sustainable buildings. This program seeks to raise the bar for all sustainable buildings by setting performance-
based standards which give merit to projects that achieve real-world results rather than credit for simply applying best-practices in the design and construction phase. The living building challenge is considered by many industry professionals to be the pinnacle of sustainable building design, although it is also recognized that these projects require significant funding to achieve such idealized goals. Recently, the US Green Building Council officially recognized the Living Building Challenge and offered a statement claiming that satisfaction of the Living Building Challenge’s Energy and Water requirements could be used to contribute to LEED points under its current iteration.