As part of Cuningham Group Architecture’s 50th Anniversary celebration, we launched a year-long program to increase awareness and review practices that support sustainable design throughout our offices in the United States. Over the course of the year, we are assessing our firm’s impact in a number of areas, ranging from water and energy usage to waste, transportation and fitness. Presented below are our recent findings on plug loads and daylighting.
Plug load is the name given to energy used by devices connected to an outlet. Devices that contribute to plug load usage include computers, printers, task lights, vending machines, device chargers and more. In commercial buildings such as our own, plug loads generally account for 25 percent of office electricity use. However, in offices with improved lighting and HVAC systems, this number can be as high as 50 percent. While this might not seem striking, one must consider the fact that plug loads are growing at a rate of 2.2 percent per year in the United States. Because of this, efficiency is reduced, potentially negating progress made by other sustainability developments.
With this information in mind, we measured the total energy use by all equipment for each office, the percentage of power for each type of equipment (laptops, desktop, monitors, coffee machines, etc.) and the power density measured in watts per square foot for each office location. This helped us estimate the percentage of our usage that is controllable.
What can we do with this information?
• Unplug unused devices
• Turn off devices not in use
• Set monitors to turn off after 5-20 minutes of inactivity
• Set computers to sleep after 15-60 minutes of inactivity
• Deploy advanced power strips
• Upgrade to more efficient appliances
Lighting and Daylighting
Within the United States, electric lighting accounts for roughly 25 percent of electricity use in all buildings. This, combined with numerous studies which show daylighting to be beneficial for both staff and employers, means that we must constantly consider how our offices are lit.
In an effort to assess the lighting in our buildings, each of our U.S. offices was given a light meter to map daylight zones. Additionally, we counted ceiling light fixtures to determine our Lighting Power Density (LPD)* and worked through a Spatial Daylight Autonomy (sDA)** analysis of the results. Going forward, we will be looking at the automation of our lighting circuits to determine if their programming can be more effective. On a larger scale, we will also be analyzing the specific ways in which our offices utilize daylighting in order to refine efficiency.
*LPD: Lighting Power Density is a lighting power requirement defined as watts of lighting per square foot of room floor area (W/sf), and is used to calculate potential energy savings or waste.
**sDA: Spatial Daylight Autonomy uses hourly illuminance grids to determine how much daylight a given space receives during standard operating hours.