Green building metrics every architect should know
There are now many resources available to support the design of more sustainable buildings and to assess the “green-ness” of these designs. As the field of sustainable design evolves, many in the field are thinking about measuring the actual benefits of these designs—the performance of buildings that we consider “green.” Numerous projects are attempting to define the qualitative and/or quantitative measures of sustainability and the data needed to implement and assess these measures.
There are certain metrics that architects should know about green buildings. These metrics help in measuring the building performance and help in comparing their equivalent buildings. Following are some of the major building performance metrics:
1. EUI/EPI (kwh/m2/year)
EUI is an abbreviation for Energy Use Intensity and EPI is an abbreviation for Energy Performance Index. EUI is expressed as the energy per square foot per year (kBtu/ft2/yr) or kWh per square metre per year (kWh/m2/yr). By calculating the EUI, architects can better predict the project’s cost, which is directly linked to a building’s energy consumption and expenditure. With Cove.tool, architects and engineers can calculate ballpark results in minutes, helping teams understand big picture components without wasting time to prep models and set up engineering inputs.
Fig. Energy use intensity (EUI)
2. sDA (Spatial Daylight Autonomy)
Daylighting is the process of using natural sunlight to light a building to help reduce energy costs, especially in commercial buildings. The process of daylighting includes controlling how much natural light (both diffuse and direct) enters a building.
Spatial daylight autonomy is a measure of daylighting in a building. Spatial Daylight Autonomy (sDA) describes how much of a space receives sufficient daylight. Specifically, it describes the percentage of floor area that receives at least 300 lux for at least 50% of the annual occupied hours
Fig. Daylight Autonomy (DA), Medium used: andrewmarsh.com
3. Carbon Emissions (Ton/CO2e/yr)
Carbon emissions are expressed as the equivalent tons of CO2, Carbon Dioxide, generated annually by the process of supporting human activity. Thus, the metric allows for a tangible measurement, in kilograms/year, of the impact and extent the building has on the atmosphere. In construction, the value of designing with carbon emissions in mind is more imperative than ever. Buildings contribute to 40% of the total carbon emissions in United States, this number changes by each city. For example, in the city of Atlanta, buildings contribute close to 60% of total carbon emissions! Global Warming continues to affect our cities and the impact is forcing the industry to change. Owners and occupants are increasingly conscious of the landscape we build and the Ton/CO2e/yr allows us to illustrate a quantitative bottom line.
4. LEED Points
Building performance certifications attract tenants, students, and
desired talent to facilities. It’s been proven that certified buildings
earn more $/sf in rent. With certification systems like LEED (USGBC),
WELL Building, Green Globes and more, project teams everywhere must
continue to evolve if they want to keep up and meet the higher building
and sustainability standards of today. LEED Points, in particularly, are
a very useful metric to understanding various aspects of a building’s
performance. For example, LEED’s EAc2 – Optimize Energy Performance
credit which measures the percent improvement from baseline energy
performance to assign x’ number of points. The higher the percentage of
improvement – the greater number of LEED points, thus a building of high
performance, higher expected savings, and happier owners and building