Green, zero energy and energy-efficient buildings

This blog is an excerpt of a piece originally posted by Consulting Specifying Engineer on June 25, 2020. Read the full article on the Consulting Specifying Engineer website
Written by Paul Erickson.

Green buildings and sustainability in the built environment have enjoyed significant momentum and adoption in the past 10 to 15 years. The prominent mainstreaming of sustainability and fairly widespread recognition of green buildings might obscure what are in fact 30-year roots to the green building movement. With the formation of the AIA Committee on the Environment in 1989, the founding of the U.S. Green Building Council in 1993 and the “Greening of the White House” in 1993, a nascent movement began to take shape in the United States.

Figure 2: State-by-state status of energy code adoption is shown as of 2018. Courtesy: Affiliated Engineers Inc.

Across the Atlantic, the U.K.-based BREEAM rating system was launching around this same time. Its first version, launched in 1990, assessed new office buildings. Energy was a major focus of these and other early green efforts — so much so that the USGBC emphasized energy in the title of its LEED rating system.

Launched in 1998, the first version of LEED not only emphasized the importance of energy efficiency, but also established a broader understanding of and advocacy for environmental resource stewardship. Site, water, energy, materials and indoor environmental quality categorically gave breadth to the concerns and impacts tied to the built environment. These raised such issues as mass transit, native ecosystems, stormwater management, refrigerant impact on the ozone, global warming, material reuse, local purchasing, indoor air quality and occupant comfort.

Such breadth was an early challenge to design teams and the owners they were serving, while energy’s “head start” established a level of familiarity as well as defined metrics for assessing opportunities and their related economics. Whether for that association or the gathering focus at the time that most energy was tied to fossil fuels, energy efficiency became synonymous with green buildings to many.

There was an expectation that the greener the building, the more energy efficient it must be and critics of LEED often pointed to underwhelming — or what was seen to be deficient — energy performance. In 2008, the New Buildings Institute published a report funded by the USGBC and the U.S. Environmental Protection Agency evaluating the energy performance of LEED buildings. The report revealed that many were performing worse than anticipated (modeled) and some were even performing below code.

With green building rating systems there has long been the risk of conflating high levels of green performance with a requisite high level of energy efficiency, but the reality is that energy usage is just one of the many metrics of a broader set of values and strategies to reduce environmental impact and improve the built environment. While some owners and project designers found it easier initially to focus on energy, something more quantitative and familiar, others prioritized other metrics and categories as reflecting their values and objectives.

Thus, a “green building” becomes something not as easily compared one to another, even when a scoring rubric facilitates point tallies resulting in tiers of outcomes (i.e., LEED certified, silver, gold and platinum; 1 to 4 of Green Building Initiative’s Green Globes).

The growing recognition of this dynamic led many entities to begin specifying energy, water and other targets to ensure that the desired performance of within one or multiple categories would be reflected in the metrics (outcomes) of the green building rating systems. This effective prioritization of credits for each owner organization has been intended to reflect their values. Energy has been one of the most common examples, with many colleges and universities, certain states and the federal government setting targets to try to ensure that a high level of energy efficiency is indeed a major attribute of their own green buildings.

One advantage of this and even of the prerequisite energy performance targets of the rating systems themselves (i.e., 5%, 10% better), has been that in many cases, projects were pushed to go beyond code. Because the rating system versions were continually changing to subsequent versions of Standard 90.1, many projects were pressed to exceed what would have been code-minimum in their respective states, whether based on Standard 90.1 or IECC.

“Energy efficiency” continues to have meaning, at least as something better than code, but the evolved expectations of many in the design community and beyond have set the target for energy savings much, much higher, such that energy efficient simply doesn’t fully connote what’s expected. That said, tangible benefits the industry has seen from energy being an integral component, if not the driver, in green building design include:

  • Energy modeling tools (whole building, single zone, façade).
  • Aa new vocabulary around energy usage metrics and target-setting that facilitates change and benefits other rating system categories.
  • Promoting life cycle cost analysis, life cycle analysis and carbon accounting.
  • Renewables positioned as tangible and practical.
  • Integrated decision making for energy, heating/cooling loads, daylighting, occupant comfort.