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What are the basics of ASHRAE 90.1?

ASHRAE 90.1 is an energy standard developed by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE), providing a basis for the design of energy-efficient buildings. This post explores the basics of the ASHRAE 90.1.

ASHRAE 90.1 is a comprehensive energy efficiency standard covering a wide range of topics, including building envelope, lighting, HVAC systems, and water heating. It is designed to reduce energy consumption and improve the overall energy efficiency of buildings.


ASHRAE Standard 90.1 focuses on sustainability and overall energy efficiency

The standard is updated regularly to reflect the latest advances in HVAC energy efficiency technology.


It’s important for architects, engineers, and building owners to understand the standard’s requirements, as ASHRAE 90.1 applies to the design, construction, and operation of all commercial buildings.


What are the intended benefits of ASHRAE 90.1?

The standard is divided into three parts: the Energy Standard for buildings (except low-rise residential buildings), the Energy Standard for low-rise residential buildings, and the Energy Standard for building systems and equipment. Each part contains specific requirements for energy efficiency, such as minimum insulation levels, lighting controls, and HVAC system design.

In light of its components, ASHRAE 90.1 is an important tool for reducing energy usage and costs in buildings and building systems. The standard also includes guidance on how to calculate energy savings and how to document compliance. By setting a uniform standard for the industry, it makes it easier to assess compliance and encourages the adoption of energy-efficient technologies.

This helps to lower energy usage and costs, improve indoor air health, indoor air quality, comfort, and reduce greenhouse gas emissions.

In addition, it helps to ensure that buildings are designed and constructed in a way that is energy efficient and cost effective. When adhering to ASHRAE 90.1, buildings can reduce energy usage and costs through improved HVAC efficiency, enhance indoor air quality through ventilation, filtration, and other methods, and maintain a baseline thermal comfort level. In addition, as a uniform industry standard, ensuring a building meets its criteria makes it easier to assess building compliance and other sustainability goals.


ASHRAE 90.1 Compliance

Because compliance with ASHRAE 90.1 is a requirement for all commercial building projects, it is important for architects, engineers, and contractors to understand these requirements and how to meet them to ensure that building projects move quickly, meet sustainability standards, and improve ROI through reduced energy costs and consumption. These standards apply to HVAC and include: minimum system features, reheat limitations, fan power, and beyond.

Changes in HVAC requirements include: minimum system features, limitation on reheat, limitation on fan power, as well as some smaller changes.

First published in 1975 and updated several times, ASHRAE 90.1 standards can provide numerous benefits, including improved energy efficiency, cost savings, and improved occupant comfort and safety.

New Metrics and Guides

Along with new definitions for sites and buildings, an informative guide is also available from ASHRAE on alternative performance metrics to existing energy cost measure using carbon emissions, site energy, or source energy.

According to Drake Erbe, the chair of the Standard 90.1 committee, the goal of this version, like those before it, is to "create a consensus standard that saves energy, is technically feasible, and cost effective",

The baseline energy cost budget used in 90.1 was established using building performance simulations to model buildings with the same size and program as the project building, and built according to the prescriptive requirements of ASHRAE 90.1 (sections 5-10). Using this model, building teams can establish a baseline energy cost budget to help building operators plan and adjust accordingly before the project is finished.

In practical applications, this analysis is revealed in terms of “% better than ASHRAE,” meaning a building could perform 30% better than the standard’s recommendations. Measuring against ASHRAE 90.1 is the basis for the LEED rating system, which awards energy points to buildings.

Essentially, ASHRAE 90.1 is another example of the industry’s commitment to sustainability and greenhouse gas reduction. That said, following these guidelines can yield some major benefits for building owners and operators, allowing them to reinvest these energy savings into other building-related programs.

For more information on ASHRAE 90.1, visit their site here.


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