What to do When ASHRAE Turns the Lights Off on You?

Impacts of ASHRAE 90.1 New Energy Code

By Jason Gergotz, Sr. Electrical Engineer

As we make our way through the remnants of a cold winter into spring and warmer weather, it is a good time to review updated building energy codes. What better way to think of warmer times ahead than by sitting down with a cup of coffee and a new code book? So, let’s sit back and conserve our energy by catching up on the standard for conserving energy – ASHRAE 90.1.

ASHRAE 90.1 is an international standard that provides the minimum requirements for energy efficient designs for buildings (except for low-rise residential buildings). Originally published in 1975 as ASHRAE 90, it was developed in the aftermath of the energy crisis of 1973. The standard was changed to 90.1 in 2001 and has been updated every three years since to reflect newer and more efficient technologies. It includes prescriptive requirements for the building envelope, HVAC, domestic hot water, power, lighting and electrical equipment with motors or pumps.

The United States does not have a national energy code or standard, so the energy codes are adopted at the state and local levels of government. Because of this, the codes and editions vary between states and even within states (i.e. commercial buildings can follow one edition, while low-rise residential follow another edition). The Department of Energy maintains information on the energy codes adopted and provides technical assistance to states and localities as they adopt and enforce energy codes. The map below shows which energy code each state has adopted for commercial buildings as of December 2017.

Although the map’s title is for commercial buildings, industrial buildings are also generally covered by the same energy code requirements. These buildings are quite different in their energy usage and these differences can affect the building envelope, HVAC design and even lighting controls. In addition, ASHRAE 90.1 contains exemptions where worker safety comes into play. Certain jurisdictions even have their own exemptions to 90.1 that buildings must follow. Contacting the local authority having jurisdiction (AHJ) will help dictate which requirements and exemptions must be followed.

The differences between ASHRAE 90.1 editions can add additional cost to the design and construction of buildings. For the sake of this article, let’s look at how the latest adopted edition in some states, ASHRAE 90.1-2013, can affect electrical design costs:

  1. Automatic Receptacle Control – permanently marked receptacles shall be controlled by either a time-of-day schedule, an occupant sensor, or an automated signal from another control or alarm system. Quantities of controlled receptacles shall be:
    1. A minimum of 50% of all 125-volt, 15- and 20-amp receptacles in all private offices, conference rooms, print and copy rooms, break rooms, classrooms and individual workstations.
    2. A minimum of 25% of branch circuit feeders installed for modular furniture.
  2. Electrical Energy Monitoring – measuring devices shall be installed for new buildings to monitor each separately:
    1. Total electrical energy
    2. HVAC systems
    3. Interior lighting
    4. Exterior lighting
    5. Receptacle circuits
  3. Dry-Type Transformer Efficiency – low-voltage transformers must comply with the Energy Policy Act of 2005 with a minimum efficiency of 97%.
  4. Interior Lighting Control – automatic controls to turn off lighting in rooms except where automatic controls would risk worker safety. In addition, some rooms will require:
    1. Bi-level lighting controls to provide an intermediate step between “all-on” and “all-off” levels (between 30-70%).
    2. Automatic daylighting controls for rooms that have exterior walls with windows.
    3. Automatic daylighting controls for rooms that have skylights.
    4. Scheduled shut-off for spaces that have no exemptions.
  5. Exterior Lighting Control – automatic controls for exterior, parking, site, landscape, façade or sign lighting, including:
    1. Automatic controls to turn on and off when daylight is sufficient or insufficient.
    2. Automatic controls for façade and landscape lighting to turn off between midnight and 6 AM.
    3. Automatic controls for other site and sign lighting to reduce lighting power by 30% between midnight and 6 am, or when no activity has been detected for 15 minutes.

Now that we have rejuvenated our code knowledge, know that we have just touched the tip of this iceberg of energy information. Contact The Austin Company for more information.