Buildings: What Does “Sustainable Buildings” Really Mean?
Building professionals and the general public are talking about how we need “sustainable” and “healthy” buildings, but what does that really mean? And how do we verify that a building is really sustainable and healthy? There are available rating systems, but do they really give us the big picture of sustainability? Is there a method to measure sustainable and healthy buildings to a single result or a carbon emission number?
Many states and cities now are taking the lead on ways to lower carbon emissions. One of the biggest components is existing buildings, which currently emit 40 percent of greenhouse gases.
During the last two decades, architects and engineers have moved the goalpost of what defines a “green building,” as Net Zero and Carbon Neutral often are used to describe the latest green buildings. However, even with the most sustainable products and sophisticated modeling—unless you measure how buildings operate over time—there’s no guarantee the building will perform as expected when designed and built.
The alphabet soup of rating systems and programs on the market can be confusing to all stakeholders. Here’s one more that was recently introduced to the American marketplace: the original green building methodology BREEAM. BRE, a multi-discipline building-science center, developed BREEAM in 1990 as a science-based methodology that uses research from the built environment to set standards.
An example of how BRE turns science into standards is daylighting, a key element of sustainable building design that promotes well-being and reduces lighting requirements. In 1980, BRE experts wrote the original “daylight factor” calculations. Since then, there have been several new proposals developed by others, including the Light Energy Numeric Indicator (LENI). Despite widespread use, the LENI equations had never been evaluated in a peer-reviewed paper, so BRE Trust sponsored research that thoroughly tested these algorithms. This research resulted in improved daylight metrics that are achievable and avoid over-glazing, improving conditions for building occupants and reducing costs for building developers and owners.
HOK and BREEAM
For the last two decades, engineering firm HOK leveraged the BREEAM methodology to improve the sustainable performance of projects in the UK and Europe. One of its most-recent projects—the Cricks Laboratory in London—was awarded a BREEAM Excellence designation. BREEAM places a greater emphasis on carbon and measuring, guiding the Cricks to save almost 35,000 tons of carbon dioxide per year, which equates to a 25 percent reduction in carbon-dioxide emissions compared to a standard 2006 building. The HOK design approach included savings through the use of lean design; high-efficiency MEP plants; and the use of extensive sub-metering, presence and leak-detection systems.
To further help clients achieve sustainability goals, HOK recently announced that it will offer to its U.S.-based clients the BREEAM In-Use standard for existing buildings. A BREEAM In-Use assessment requires an evaluation of operational energy consumption and associated carbon-dioxide emissions, based on actual metered energy-consumption data. Although the average carbon-dioxide savings for BREEAM-assessed buildings is approximately 22 percent, the BREEAM methodology strongly aligns with the zero carbon agenda and encourages buildings to aspire to this level of design performance.
BREEAM encourages a risk assessment be carried out to identify and evaluate the impact of extreme weather conditions on the building over the entire projected lifecycle. The risk of extreme weather was considered for one of the most-significant infrastructure projects in the UK: Crossrail, a new high-frequency, high-capacity railway for London and the South East. Climate-change risks were identified that impacted the design, including extreme temperatures and an increase in extreme weather events. Examples of mitigation measurements included rolling stock systems designed to operate in high-temperature environments, continually welded de-stressed rail track to prevent buckling in high temperatures, and underground stations with full height doors at platform edges separating them from tunnels to allow platform areas to be mechanically cooled.
HOK and similar market-leading design and engineering firms are designing with climate change in mind. Although humans can’t measure into the future yet, using the best science now available for calculating events such as sea-level rise will help reduce the impacts and ultimately reduce carbon emissions.
In 2015, BRE made the COP21 Climate Pledge in advance of climate negotiations in Paris. The pledge is a commitment to deliver more than 9,000 certified buildings with emissions savings in excess of 900,000 tons of carbon dioxide between 2016 and 2020.
You can design and construct the greenest building in the world, but if you don’t operate it that way over its lifecycle, then it’s a terrible waste of resources. We all need to continue the conversation on how best to reduce carbon emissions from the built environment.