Documenting ASHRAE 90.1 compliance
There are three paths to ASHRAE 90.1 compliance, and documenting compliance with Standard 90.1 is not as difficult or confusing as engineers believe it to be.
By Jim Huber, NEBB CP, CEM, Complete Commissioning Inc., Annapolis, MD
ASHRAE Standard 90.1—Energy Conservation in New Buildings Except Low-Rise and Residential Buildings—was originally published in 1975. The current standard is 90.1-2010, and it was rewritten with the goal of reducing building energy costs by 30% compared to the 2004 version of the standard.
ASHRAE 90.1 addresses the energy-efficiency requirements for the design, materials, and equipment used in nearly all new construction, additions, renovations, and construction techniques. The requirements of 90.1 affect the overall energy efficiency of any structure and can reduce the energy needed to maintain a healthy, comfortable, and fully functioning indoor environment. The standard applies to:
- Building envelope
- HVAC systems, equipment, and controls
- Service water heating systems and equipment
- Lighting systems, equipment, and controls
- Other equipment.
While ASHRAE 90.1 covers many areas in a building, this article will concentrate on the HVAC requirements of ASHRAE 90.1 (Section 6 of the standard). There are several common methods available to document compliance, including prescriptive forms, software-generated forms, and modeling runs. ASHRAE also publishes the 90.1-2010 user’s guide, which can be a big help in clarifying the requirements of the standard and includes the necessary compliance forms.
ASHRAE 90.1 provides for exceptions to the compliance requirements. Simply put, the exceptions are:
- When HVAC serving a building addition is provided by existing HVAC systems and equipment (new systems installed as part of the addition still must comply with the standard)
- Equipment that is being modified or repaired but not replaced
- Where replacement or alteration of a piece of equipment requires extensive revisions to other systems, equipment, or elements of a building
- For a refrigerant change of existing equipment
- For the relocation of existing equipment
- For ducts and pipes where there is insufficient space to meet the requirements of Section 6.
The easiest method for documenting compliance with 90.1 is to download the compliance forms from the ASHRAE website. The forms are provided as PDFs and can be modified and printed. They also serve as a good template if you prefer to create compliance forms on your company letterhead. If, as we do, you place too much value on your time to “reinvent the wheel,” just use the “stock” ASHRAE form.
Once you have determined whether your building must comply with the standard, the next step is to determine the best path for compliance. Standard 90.1 gives you three options:
- The simplified approach option for HVAC systems (Section 6.3)
- Mandatory provisions (Section 6.4) required for prescriptive path (Section 6.5)
- Mandatory provisions (Section 6.4) required for energy cost budget (ECB, Section 11).
The simplified approach option for HVAC systems can reduce the effort required to show compliance for small buildings with gross floor area less than 25,000 sq ft. Many of the requirements in Section 6 do not apply to simple systems, so the small building criteria have been compiled into one section (6.3). It is intended to alleviate the designer’s burden of sorting through requirements that are not applicable while still maintaining consistent requirements with the prescriptive path.
The prescriptive compliance path may be used for any HVAC system, but it is primarily used for larger buildings and buildings with more complex systems where the simplified approach option is not applicable, such as multi-zone systems or central plants. Systems complying using the prescriptive path also must meet the mandatory provisions of Section 6.4
The energy cost budget method is intended for building systems that are unable to meet all of the prescriptive requirements or for designers who want to explore design alternatives. It allows trade-offs between various building systems and components. A computer program is used to calculate the design energy cost for a proposed building design as if all mandatory and prescriptive requirements had been met. The program is then used to calculate the energy cost for the proposed design. The energy cost for the proposed design cannot exceed the energy cost for the budget design. Systems complying using the ECB method must also meet the mandatory provisions of Section 6.4 as well as the ECB requirements in Section 11.
Documenting the simplified approach
Part 1 of the form is specifically for using the simplified approach option. It is laid out as a simple checklist for documenting compliance with each of the requirements, and is the only form required with this compliance option. There are 17 requirements in that section, and your systems must comply with every applicable requirement. You’ll still have to flip through the standard for each section to determine if you can “check the box.” If your design is in compliance with all of the 17 requirements, the next step is to fill out the equipment efficiency table to include with the submittal. There is a simplified table included at the bottom of part 1 in the compliance form you downloaded.
Documenting the prescriptive path
Part 2 of the compliance form contains the mandatory requirements specified in Section 6.4. This includes tables for documenting the equipment efficiency. Beneath the efficiency tables are 10 general requirements and five special mandatory requirements. You’ll need to check the box next to each requirement that applies to your system. If the system requirement is not applicable, just leave the box blank. Section 2 also includes a systems worksheet to help you document mandatory compliance for each air system. Part 3 of the compliance form contains a checklist of the prescriptive requirements for air, hydronic, and special systems.
All told, there are 13 requirements, and there is also a systems worksheet to help you document prescriptive compliance for each system. The compliance form also includes tables on the third page to document the standard’s fan power requirements. You can use either the nameplate horsepower option or the brake horsepower option.
Documenting the energy cost budget method
When using the ECB method, the building design must still meet the mandatory provision of the standard, not only for the HVAC requirements (Section 6.4), but also for Sections 5.4, 7.4, 8.4, 9.4, and 10.4. The mandatory requirements in each of those sections are not available for trade-off under this method. In addition to documenting compliance with the mandatory provisions, the ECB method has some additional compliance requirements, including a summary to document design energy cost versus budgeted cost.
You’ll also need to provide a list of energy-related features that exceed the standard’s requirements, as well as a list of features that are being traded off. The input and output reports from the simulation program must be provided, including an energy usage breakdown, and the number of hours the heating and cooling loads are not met for both the budget building design and the proposed building design. Any error messages provided by the program must also be explained.
The last step in documenting compliance for all paths is the submittal requirement, and it includes the following:
- Record drawings
- Record drawings must be provided to the owner within 90 days of building acceptance.
- O&M manuals: The manuals must include (at a minimum):
- Submittal data
- HVAC manuals
- Service agency
- HVAC control information
- System balancing
- Construction documents must require the systems to be balanced.
- A test and balance report must be provided to the owner for spaces greater than 5,000 sq ft.
- System commissioning
- For projects larger than 50,000 sq ft (except warehouse and semi-heated spaces), the instructions for commissioning the HVAC system must be provided by the system designer in the project plans and specifications. These instructions are also included in the record drawings provided to the owner.
Documenting compliance with ASHRAE 90.1-2010 is a straightforward process, as long as you follow a systematic approach. The checklists and tables provided in the standard are not a submittal requirement, but are an invaluable tool in ensuring that you are not missing any of the requirements. This article has provided an overview of each of the three paths to compliance, and hopefully has shown that documenting compliance with standard 90.1 is not as difficult or confusing as many folks believe it to be.
Huber is president of Complete Commissioning, and is a National Environmental Balancing Bureau (NEBB) Certified Professional and a Certified Energy Manager.