ASHRAE has made over 100 changes in its energy efficiency standard for buildings, excluding low-rise residential, since the previous 2016 version. This includes numerous energy-saving measures.
ANSI/ASHRAE/IES Standard 90.1-2019 will provide clearer guidance for exceeding efficiency goals, explains Drake Erbe, chair of the Standard 90.1 committee. “This new version focuses on energy-saving measures, which we hope will reward designs for achieving energy cost levels above the standard minimum and result in more efficient buildings and more innovative solutions.”
Some significant changes include:
- Administration and enforcement: commissioning requirements were added to the standard for the first time. Section 4.2.5, “verification, testing, and commissioning,” expanded and requirements were outlined for commissioning in accordance with ASHRAE/IES Standard 202.
- Building envelope: for vertical fenestration (the arrangement of windows and doors), “non-metal framed” and “metal framed” products were combined. A minimum criterion for SHGC and U-factor were upgraded across all climate zones. The air leakage section was revised to clarify compliance. Changes to the vestibule section refined the exceptions and added a new option and associated criteria for using air curtains.
- Lighting: lighting power allowances for the Space-by-Space Method and the Building Area Method were modified. The model is more representative of real-world conditions with the inclusion of updated IES recommendations.
- Mechanical: new requirements were defined to allow designers the option to use ASHRAE Standard 90.4 instead of ASHRAE/IES Standard 90.1 requirements in computer rooms that have an IT equipment load larger than 10 kW.
- Energy cost budget method: the baseline was set for on-site electricity generation systems.
- Performance rating method: explicit heating and cooling COPs were provided without a fan for the baseline packaged cooling equipment. Rules were added for modelling the impact of automatic receptacle controls. More specific baseline rules were set for infiltration modelling. Clarification was added for how plant and coil sizing should be performed.
- Both compliance paths: rules were added related to how renewables are treated. Extensive updates were added to the rules for lighting modelling.
Also new to the standard is the use of the fan energy index (FEI) as the metric for efficiency provisions for commercial and industrial fans and blowers.
The 2019 version is the 11th edition published since the original standard was first published in 1975 during the U.S. energy crisis.