In the jurisdictions that have implemented MEPs we see a variety of different objectives, triggers, and metrics to assess and improve the energy performance of existing buildings, as shown in Table 1. Typically, most jurisdictions lean towards Energy Use Intensity (EUI) Greenhouse Gas Intensity (GHGI). These two metrics give policymakers the greatest confidence that the policy will actually meet the desired targets and place every building on the right track towards net-zero. Two approaches can be taken to apply these metrics, a reference approach or absolute performance approach.
Table 1: Leading Minimum Energy Performance Standards
| Jurisdiction (implementation date) | Objective(s) and building type | Trigger | Metric |
|---|---|---|---|
| United Kingdom (2018) | Increase private residential and commercial rental property standards and reduce energy and emissions. | Point of sale, major renovation. | Health-based metrics that include minimum energy standards, based on EPC. |
| France (2015) | Overall reduction in final energy consumption, reduce energy poverty in private rental and owner occupied residential. | Point of sale, change in tenancy. | Based on an EPC that includes EUI and minimum decent living requirements such as minimum floor area and free of pests. |
| Washington, D.C (2018) | Reduce energy and emissions from commercial and multi-family buildings (>50,000 sq. ft),. | Triggered by set timelines according to building size. Based on benchmarked performance. |
Uses the Energy Star assessment to identify buildings. Buildings must meet the median ENERGY STAR score for that building type or reduce energy use 20% |
| New York City (2019) | Reduce emissions from commercial and multi-family buildings (>50,000 sq. ft.) based on an emissions rate/square foot multiplied by the building's footprint. | Captures highest emitting buildings between 2024-2029. Second compliance period between 2030-34 will affect approx. 75% of covered buildings (>50,000 sq. ft.). |
GHG intensity limits, expressed in CO2 eq. / sq. ft for 10 building categories. |
| Reno, Nevada (2019) | Reduce energy and water use in commercial and multi-family buildings (> 30,000 sq. ft). | Triggered by size threshold and by year for specific archetypes. | Energy Star score or EUI as compared to all covered buildings. Water use intensity. |
| Vancouver (June 2021 - commercial/multifamily and 2022 - detached homes. | Reduce fossil fuels use in building operations, including space and water heating. Applies to each major building type. | Performance requirements increase in roughly 5-year intervals until all buildings achieve zero emissions by 2030, and for many building types, by 2025. | GHGI limits and Thermal Energy Demand Intensity (TEDI). |
The reference approach, also known as the percent better approach, establishes a typical reference building archetype based on the performance of existing buildings. Performance data is collected through benchmarking programs to establish a reference building based on attributes such as building age, size, type of use and occupancy, and typical building envelope measures and mechanical systems. The building's performance is then expected to be improved above the average or median performance of the stock for that building type. This approach demands accurate reference building modeling to ensure the targets set from this data are feasible, achievable, and avoid disproportionately burdening building owners, while also ensuring each building is put on a path towards net-zero.
The reference approach can be helpful in defining an approximate representation of the energy and emission profiles of a typical building in a specific category. Nonetheless, the final impact of the reference approach can be uncertain; the baseline can be gamed and a percentage reduction doesn't provide certainty that a building is hitting a standard consistent with net-zero emissions. Instead, an absolute performance approach is preferable given the simplicity of setting and achieving clear energy and emissions targets. Like the reference approach, an average standard of building performance is established for specific archetypes. All buildings then receive a limit based on a set total energy or emissions metric per square metre of floor area. Absolute performance criteria have the advantage of making compliance a clear and straightforward affair, and can better ensure we actually meet our energy efficiency and GHG reduction goals.