ASHRAE Standard 90.1 has served as a target for commercial building energy codes and a basis for standards and codes globally for nearly 50 years. Standard 90.1 outlines the minimum requirements for energy-efficient design of sites and buildings, excluding low-rise residential buildings.
It details energy efficiency requirements when designing and constructing new sites and buildings and for the systems, new building additions and systems, and the new systems and equipment in existing buildings. Builders and engineers can also learn about the requirement’s compliance criteria.
What are the ASHRAE 90.1-2022 Revisions?
The current ASHRAE Standard 90.1-2022 revised the 2019 energy efficiency standard with over 80 addenda. The revisions focus on the whole system changes and how a building’s systems interact, compared to a prescriptive-based component design. Standard 90.1-2022 has an expanded scope to include buildings and sites, new energy credit provisions for a tailored approach to enhance energy efficiency, guidance on using carbon emissions, site energy, or source energy as alternative performance metrics to the current energy cost standard, and efficiency improvements in IEER for commercial rooftop units and the introduction of SEER2/HSPF2 metric for air-cooled heat pumps under 65,000 capacity.
New additions to the energy standard or code include:
- Minimum mandatory requirement for on-site renewable energy systems
- Optional Mechanical System Performance Path enabling HVAC system efficiency tradeoffs using the new total system performance ratio (TSPR) metric
- New provisions to mitigate the effects of thermal bridging
What is IEER?
The Integrated Energy Efficiency Ratio (IEER) is the newest rating for HVAC energy efficiency and is slowly replacing the former EER rating and the newer SEER rating. Created in the 1970s, the EER rating is a basic and fairly inaccurate metric that is used in portable and window air conditioning units. The SEER rating was released in 2008 to account for real-climate conditions and is used to estimate the energy efficiency of mini split AC units and central ACs.
Established in 2015, IEER is the most comprehensive real-world energy efficiency rating designed to estimate the performance and running costs of AC units. It measures two factors not accounted for by the other energy efficiency ratings for air conditioners – different loads of AC units and different temperatures. Full load, considered 100%, accounts represent only 2% of the total IEER rating as well as part loads that include 25%, 50%, and 75% loads. The SEER rating accounts for part loads. IEER also looks at the air conditioning units performance at various outdoor temperatures, whereas SEER only measures performance at 95 degrees F.
How Does ASHRAE Drive Efficiency?
The addition of the IEER rating efficiency increases for commercial rooftop units provides significant cost-effective energy savings. IEER’s expanded load measurements inspire variable-speed operation within the design, which enhances dehumidification performance in humid regions. ASHRAE 90.1 works with industries collaboratively to continue improving HVAC equipment and building processes.
A building’s operational cost is affected by energy efficiency, which includes heating, cooling, lighting, and electrical systems. Following ASHRAE 90.1 standards helps building owners significantly reduce energy consumption, and some municipalities have adopted standards for their building codes. Incorporating these standards into the design and construction practices means buildings abide by current regulations and owners do not need to worry about the legal penalties, fines, or delays related to non-compliance.
Tenants also benefit from this energy efficiency as their values align with environmental consciousness. Attracting tenants is competitive and linked to a property’s energy performance, especially with many large occupiers pledging net-zero emissions goals and wanting buildings that align with that. A building’s energy efficiency ranking reduces operational costs and meets corporate goals for LEED green building ratings.
