Welcome to Part VII of our ongoing series breaking down ASHRAE standards and their impact on modern commercial HVAC design, energy efficiency, and indoor environmental quality (IEQ).
Commercial buildings are becoming more energy efficient thanks to standards like ASHRAE 90.1, but sustainability means more than just lower energy bills. For a more comprehensive approach, ASHRAE developed Standard 189.1. This standard provides a code-enforceable blueprint for the design, construction and operation of high-performance green buildings.
In this installment of our ASHRAE Standards series, we’ll learn about Standard 189.1 for high-performance green buildings and how ERVs can help with meeting this standard.
What Is ASHRAE Standard 189.1?
Formally titled Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings, Standard 189.1 was created through a collaboration between ASHRAE, the U.S. Green Building Council (USGBC), the Illuminating Engineering Society (IES). It focuses on comprehensive sustainability goals, including building location, energy efficiency, water usage, building materials, and a healthy indoor environment.
Unlike voluntary green certification programs, Standard 189.1 is written in mandatory, enforcement-ready code language. This makes it easy for local jurisdictions to adopt directly into law or for companies to mandate the standard in contract documents.
In 2018, Standard 189.1 reached a major milestone: it was integrated as the technical content for the International Green Construction Code (IgCC). Today, when a city or state adopts the IgCC, they are adopting the technical provisions of Standard 189.1.
What Are the Key Focus Areas of Standard 189.1?
ASHRAE Standard 189.1 organizes its technical requirements across six key focus areas to address the full lifecycle and environmental impact of a building.
1. Site Sustainability
Standard 189.1 mandates smart land use to minimize environmental impact and preserve local biodiversity. This includes reflective roofing to minimize cooling requirements, and exterior lighting limits to protect night skies and surrounding habitats. Buildings also need to avoid development on floodplains and must provide EV charging infrastructure and bicycle storage.
2. Water Use Efficiency
Reducing water usage is critical to achieving sustainability goals. Standard 189.1 requires low-flow plumbing fixtures and high-efficiency appliances, plus smart irrigation systems and limits to turf grass coverage. Buildings also need sub-metering for major water-consuming systems to track usage and find inefficiencies.
3. Energy Efficiency
Using Standard 90.1 as a foundation for energy efficiency, Standard 189.1 pushes energy performance requirements even further. These directives include tighter building envelopes, lower lighting power density, higher efficiency minimums for HVAC equipment, and expanded use of energy recovery ventilators (ERVs). Buildings also need to provide on-site renewable energy systems and reduce power consumption during off-hours.
4. Indoor Environmental Quality (IEQ)
Standard 189.1 also requires that buildings provide a healthy and comfortable indoor environmental quality (IEQ) for occupants. This includes indoor air quality (IAQ), emissions from materials, heat and humidity management, noise control, and daylight minimums. For IAQ, the standard mandates enhanced ventilation rates, outdoor air delivery monitoring, filter minimums, and continuous air quality management. In addition, buildings need to limit volatile organic compounds (VOCs) and use low-emission materials in their paints, sealants, adhesives, flooring, and composite wood products.
The standard also regulates temperature and humidity levels. High-performance buildings are sealed tight for energy efficiency, which means moisture can accumulate and cause discomfort for occupants and mold growth. For acoustic control, buildings need to limit sounds coming in from outside, interior sound transmission, and noise from HVAC systems. Finally, buildings must provide access to daylight for 50% of their floor area, and control for solar glare through shades, louvers, or other methods.
5. Materials and Resources
To lower their carbon footprint, buildings are required to use a certain percentage of recycled building materials, locally-sourced products and sustainably harvested wood. The standard also puts limits on waste from construction, and requires the building to offer recycling and separate disposal of hazardous materials for occupants.
6. Construction and Plans for Operation
The final focus area for Standard 189.1 is verifying the building is in compliance and providing a plan to maintain these requirements. Buildings must undergo testing and commissioning to verify all mechanical, electrical, and water systems operate as designed. The building operator also needs long-term operational plans for preventive maintenance, continuous energy and water monitoring, and indoor air quality maintenance throughout the building’s lifecycle.
How Can Buildings Achieve Standard 189.1 Cost Effectively?
With all the regulations listed above, it may seem that achieving Standard 189.1 would be cost-prohibitive for building projects. However, architects and engineers can achieve Standard 189.1 cost-effectively by leveraging integrated design and right-size mechanical infrastructure, reducing upfront capital costs and long-term operating expenses.
The most impactful strategy centers on total energy recovery ventilation and dedicated outdoor air systems (DOAS), which use exhaust air energy to precondition incoming outdoor air. Since HVAC systems account for the 40–50% of energy use in commercial buildings, this makes it one of the best opportunities to find cost savings.
ERVs Reduce Ventilation Energy Loads
ASHRAE Standard 189.1 presents buildings with a central tension: increasing ventilation rates to improve IEQ without exceeding energy efficiency caps. With ERVs, buildings can dramatically lower their heating and cooling loads while providing the high ventilation rates needed to achieve strict IEQ standards.
ERVs work by capturing the total energy (heat and moisture) from exhaust air and using it to pre-condition incoming outdoor air. With RenewAire ERVs, buildings can reduce their ventilation energy loads by up to 70%.
ERVs also allow buildings to save money on capital costs with smaller HVAC equipment. Outdoor air enters the HVAC system preconditioned, lowering peak heating and cooling capacity requirements. This allows engineers to specify smaller chillers, boilers, and compressor systems, saving on construction costs.
DOAS Systems Optimize Outdoor Air Delivery
Standard 189.1 also requires frequent outdoor air changes as part of its ventilation and IEQ requirements. However, traditional HVAC systems struggle to control humidity when ventilation rates are high. In fact, outdoor air typically accounts for more than 80% of a building’s dehumidification load.
With dedicated outdoor air systems (DOAS), buildings can decouple outdoor air demand and humidity control from local heating and cooling equipment, allowing both systems to operate more efficiently. DOAS systems also integrate easily with CO2 and occupancy sensors to provide outdoor air as needed, conserving energy during low occupancy periods.
Using energy recovery technology, buildings can optimize their HVAC systems through energy efficiency and ventilation decoupling to achieve Standard 189.1 more cost effectively.
Achieve ASHRAE Standard 189.1 with Energy Efficiency
ASHRAE Standard 189.1 bridges the gap between basic building codes and ambitious green certifications. By providing clear, enforceable rules for energy, water, materials, and occupant health, it helps turn sustainable design from a voluntary luxury into standard industry practice.
Achieving the stringent ventilation and IEQ mandates of ASHRAE Standard 189.1 does not have to come at the cost of high utility bills. By integrating DOAS and ERV units into HVAC systems, high-performing buildings can continuously deliver outdoor air changes while reducing ventilation energy loads and lowering operational costs.
Frequently Asked Questions (FAQs)
What are the differences between ASHRAE Standard 90.1 and 189.1?
| Feature | Standard 90.1 | Standard 189.1 |
| Primary Scope | Energy efficiency strictly (building envelope, HVAC, lighting, water heating) | Whole-building sustainability (site, water, energy, indoor environmental quality, materials) |
| Performance Level | Baseline minimum energy efficiency requirements | High performance / beyond-code green building standard |
| Core Intent | Reduce energy consumption and cost across commercial buildings | Minimize environmental footprint across life cycles |
| Building Code Role | Adopted directly or serves as the reference base for energy codes (IECC) | Serves as the technical content for the International Green Construction Code (IgCC) |
| Water Efficiency | Limited (focuses mostly on hot water heating equipment efficiency) | Comprehensive (indoor water use, outdoor irrigation, stormwater) |
| Indoor Quality & Site | Not in scope | Mandatory requirements for site selection, heat island effect, IAQ, and acoustics |
What are the changes to ASHRAE Standard 189.1-2023?
The latest edition of ASHRAE Standard 189.1 was published in 2023. It introduces major updates aimed at lowering embodied carbon, expanding renewable energy integration, and strengthening climate resilience.
Key Changes and Updates:
- Enhanced IAQ & Particulate Filtration: Updates filtration mandates for outdoor air delivery systems, explicitly refining particulate matter removal criteria to align with elevated IAQ benchmarks.
- Decarbonization & Electrification Support: Realigns energy provisions with ASHRAE Standard 90.1 updates, placing greater emphasis on electrification-ready infrastructure, grid-interactive efficient building features, and peak-demand management.
- On-Site Renewable Energy & EV Infrastructure: Increases baseline requirements for on-site solar power generation and expands mandatory electric vehicle infrastructure in parking facilities.
- Climate Resilience Framework: Incorporates new provisions for building resilience, including risks from extreme heat, flooding, power outages, and wildfire smoke to ensure continuity of critical operations.
- Embodied Carbon & Material Life-Cycle: Expands requirements for environmental product declarations and introduces stricter limits on embodied carbon for structural and enclosure materials.
- Water Efficiency & Metering: Tightens indoor plumbing fixture efficiency targets and mandates expanded sub-metering for high-volume water systems like cooling towers and irrigation networks.
Why do cities adopt ASHRAE Standard 189.1?
Cities adopt ASHRAE Standard 189.1 primary because it gives municipalities a legally enforceable, consensus-backed regulatory framework to mandate green building practices across all new commercial construction.
Rather than relying on voluntary programs or creating complex local green codes from scratch, cities adopt Standard 189.1 for key strategic reasons:
1. Transform Green Building from Voluntary to Mandatory
Voluntary rating systems like LEED encourage top-tier developers to build sustainably, but don’t regulate commercial construction beyond standard energy codes. Adopting Standard 189.1 allows a city to make high-performance sustainable practices a legal requirement for all covered projects.
2. Turnkey Integration into Local Building Codes (IgCC)
Standard 189.1 provides the entire technical backbone for the International Green Construction Code (IgCC). Because it is written in strict regulatory « code language, » city building departments can adopt it off the shelf. It seamlessly overlays existing baseline codes like the International Building Code (IBC) and ASHRAE Standard 90.1. This helps reduce jurisdictional conflicts during plan reviews and inspections.
3. Achieving Local Climate and Decarbonization Targets
Many cities have established ambitious municipal goals to reduce carbon emissions, lower water consumption, and build resilience against extreme weather. Standard 189.1 offers pre-packaged regulatory mechanisms to enforce those goals locally.
4. Protecting Public Health and Infrastructure
Beyond energy savings, cities adopt 189.1 to protect local public assets and community health. Enhanced IAQ improves the health and productivity of occupants, while strict indoor/outdoor water-efficiency mandates reduce strain on municipal water systems and wastewater treatment plants.