What is ASHRAE 90.1?

June 17, 2021

ASHRAE 90.1 is a standard for measuring energy in commercial buildings. It covers many aspects of energy management, such as total consumption, HVAC and lighting systems, and individual circuits. For buildings over 10,000 square feet, with or without tenants, it is more cost effective to have multi-load, branch circuit, and high-density monitoring equipment. In buildings with tenants, both individual and total building usage need to be monitored every 15 minutes at a minimum and be recorded hourly, daily, monthly, and annually.

There are many conditions that need to be met to fully comply with the ASHRAE 90.1 standard, but at the heart of the energy monitoring section of the standard is the Chapter Monitoring section, which requires the separate monitoring of each of the following:

  • Total energy consumption for the entire building
  • HVAC systems
  • Interior lighting
  • Exterior lighting and receptacle circuits 

Multi-load meters enable a cost-effective solution to meet this chapter in particular.

Challenges with ASHRAE 90.1

There are several potential challenges for monitoring building systems. In retrofit installations, one of the biggest challenges is the building circuits themselves. Often the circuits in older construction are shared in multiple panels throughout the building. This means either the circuits need to be split out to measure the data in order to get accurate data or the data must be collected at each panel for reporting purposes without the necessary granularity.

The next challenge is that older electrical installations could have multiple voltage and phasing configurations in the same location. This means multiple building systems can come from a single location with different power sources. Depending on the types of loads on a panel, the loads must either be disaggregated or aggregated. A panel with both interior lighting and HVAC loads and must be disaggregated, whereas all the lighting loads must be aggregated for a total sum for the building.

A third challenge is any data from energy meters must be stored for 36 months as part of the overarching system in order to comply with the standard. If a system is not in place to record those values, one must either be put in place or data must be stored in a secure traceable manner.

Multi-Load Power Meters for ASHRAE 90.1setra-systems-power-meters

Multi-load monitoring is useful for compliance to ASHRAE 90.1. Meters with multi-load capabilities provide much more granular data than a meter that only measure a single three-phase load. Also, meters with dual voltage inputs allow users to meter two different service types and voltage levels from a single power meter. Users can measure both 120V and 480V, for example, at the same time on a multi-load meter with dual voltage inputs.

Topics: Energy Management