Purchasing Energy-Efficient Commercial Boilers

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The Federal Energy Management Program (FEMP) provides acquisition guidance for commercial boilers, a product category covered by FEMP-designated efficiency requirements. Federal laws and requirements mandate that agencies purchase ENERGY STAR-qualified or FEMP-designated products in all product categories covered by these programs and in any acquisition actions that are not specifically exempted by law.

FEMP's acquisition guidance and efficiency requirements apply to gas- or oil-fired, low-pressure hot water or steam boilers used in commercial space heating applications with a rated capacity between 300,000 and 10,000,000 Btu/h. High-pressure boilers (i.e., those used in industrial and cogeneration applications) and residential boilers (i.e., those with a capacity less than 300,000 Btu/h) are excluded. Residential boilers are covered by the ENERGY STAR program and are excluded from this product category.

This acquisition guidance was updated in July 2016.

Find Product Efficiency Requirements

Federal purchases of commercial boilers must meet or exceed the minimum efficiency requirements and thermal efficiencies listed in Table 1. These efficiency levels can be voluntarily adopted by non-federal organizations, institutions, and purchasers.

Table 1. Efficiency Requirements for Commercial Boilers
Product ClassRated CapacityFuelHeating MediumThermal Efficiency* (%)
Small Gas-Fired Hot Water≥300,000 Btu/h and ≤2,500,000 Btu/hGasHot WaterEt ≥ 95.0
Large Gas-Fired Hot Water>2,500,000 Btu/h and ≤10,000,000 Btu/hGasHot WaterEt ≥ 94.0
Small Gas-Fired Steam≥300,000 Btu/h and ≤2,500,000 Btu/hGasSteamEt ≥ 81.0
Large Gas-Fired Steam>2,500,000 Btu/h and ≤10,000,000 Btu/hGasSteamEt ≥ 83.0
Small Oil-Fired Hot Water≥300,000 Btu/h and ≤2,500,000 Btu/hOilHot WaterEt ≥ 85.5
Large Oil-Fired Hot Water>2,500,000 Btu/h and ≤10,000,000 Btu/hOilHot WaterEt ≥ 86.0
Small Oil-Fired Steam≥300,000 Btu/h and ≤2,500,000 Btu/hOilSteamEt ≥ 84.0
Large Oil-Fired Steam>2,500,000 Btu/h and ≤10,000,000 Btu/hOilSteamEt ≥ 85.5
*Based on Hydronics Institute, Method to Determine Efficiency of Commercial Space Heating Boilers (HI BTS-2000, Rev. 06.07).


Make a Cost-Effective Purchase: Save $23,000 or More by Buying a FEMP-Designated Product

FEMP has calculated that the required model gas-fired, hot water commercial boiler saves money if priced no more than $23,000 above the less efficient model. The best available model saves the average user more: $28,000 in lifetime energy costs. Table 2 compares three types of product purchases and calculates the lifetime cost savings of purchasing efficient models. Federal purchasers can assume products that meet FEMP-designated efficiency requirements are life cycle cost-effective. To view the full results and assumptions for this scenario, use FEMP's commercial boiler calculator default settings (choose "new," "water," and "gas").

Table 2. Lifetime Energy Cost Savings for Efficient Gas-Fired, Hot Water Boilers
PerformanceBest AvailableFEMP-DesignatedBase Model
Thermal Efficiency (%)
Lifetime Energy Cost Savings$28,000$23,000======
View the Performance and Model Assumptions for Table 2
Performance Column

Thermal Efficiency (%): Represents a boiler's energy output divided by energy input as defined by ANSI Z21.13.

Annual Energy Cost: Calculated based on an assumed natural gas price of $0.69/therm, which is the average natural gas price at federal facilities throughout the United States.

Lifetime Energy Cost: The sum of the discounted value of annual energy cost and an assumed product life of 25 years. Future energy price trends and a 3% discount rate are from Energy Price Indices and Discount Factors for Life-Cycle Cost Analysis – 2015: Annual Supplement to NIST Handbook 135 and NBS Special Publication 709 (NISTIR 85-3273-30).

Lifetime Energy Cost Savings: The difference between the lifetime energy cost of the less efficient model and the lifetime energy cost of the required model or best available model.

Best Available Model Column

Calculated based on the AHRI Directory of Certified Products. More efficient models may be introduced to the market after FEMP's acquisition guidance is posted.

FEMP-Designated Model Column

Calculated at or above the top 25% in energy performance for the product category. FEMP compares the life cycle cost of the top 25% most efficient products in a product category against the least efficient or base model products in that category. Federal agencies must purchase products that meet or exceed FEMP-designated efficiency levels.

Base Model Column

Calculated based on the minimum legal energy performance available in the market.

Determine When ENERGY STAR Products Are Cost-Effective

An efficient product is cost-effective when the lifetime energy savings (from avoided energy costs over the life of the product, discounted to present value) exceed the additional up-front cost (if any) compared to a less efficient option. ENERGY STAR considers up-front costs and lifetime energy savings when setting required efficiency levels. Federal purchasers can assume ENERGY STAR-qualified products and products that meet FEMP-designated efficiency requirements are life cycle cost-effective. In high-use applications or when energy rates are above the federal average, purchasers may save more if they specify products that exceed federal efficiency requirements (e.g., the best available model).

Commercial Boilers Cost Calculator

Users who wish to determine a product's cost-effectiveness for their application may do so using the Energy Cost Savings Calculator for Commercial Boilers.

Claim an Exception to Federal Purchasing Requirements

Products meeting ENERGY STAR or FEMP-designated efficiency requirements may not be life cycle cost-effective in certain low-use applications or in locations with very low rates for electricity or natural gas. However, for most applications, purchasers will find that energy-efficient products have the lowest life cycle cost.

Agencies may claim an exception to federal purchasing requirements through a written finding that no FEMP-designated or ENERGY STAR-qualified product is available to meet functional requirements, or that no such product is life cycle cost-effective for the specific application. Learn more about federal product purchasing requirements.

Incorporate Federal Acquisition Regulation Language in Contracts

These mandatory requirements apply to all forms of procurement, including construction guide and project specifications; renovation, repair, energy service, and operation and maintenance (O&M) contracts; lease agreements; acquisitions made using purchase cards; and solicitations for offers. Federal Acquisition Regulation (FAR) Part 23.206 requires agencies to insert the clause at FAR section 52.223-15 into contracts and solicitations that deliver, acquire, furnish, or specify energy-consuming products for use in federal government facilities. To comply with FAR requirements, FEMP recommends that agencies incorporate efficiency requirements into technical specifications, the evaluation criteria of solicitations, and the evaluations of solicitation responses.

Find Federal Supply Sources

The federal supply sources for energy-efficient products are the General Services Administration (GSA) and the Defense Logistics Agency (DLA). GSA sells products through its Multiple Awards Schedules program and online shopping network, GSA Advantage!. DLA offers products through the Defense Supply Center Philadelphia and online through DOD EMALL. Products sold through DLA are codified with a 13-digit National Stock Number (NSN) and, in some cases, a two-letter Environmental Attribute Code (ENAC). The ENAC identifies items that have positive environmental characteristics and meet standards set by an approved third party, such as FEMP and ENERGY STAR.

The United Nations Standard Products and Services Code (UNSPSC) is a worldwide classification system for e-commerce. It contains more than 50,000 commodities, including many used in the federal sector, each with a unique eight-digit, four-level identification code. Manufacturers and vendors are beginning to adopt the UNSPSC classification convention and electronic procurement systems are beginning to include UNSPSC tracking in their software packages. UNSPSCs can help the federal acquisition community identify product categories covered by sustainable acquisition requirements, track purchases of products within those categories, and report on progress toward meeting sustainable acquisition goals. FEMP has developed a table of ENERGY STAR and FEMP-designated covered product categories and related UNSPSC numbers.

Commercial Boilers Schedules and Product Codes

GSA offers commercial boilers through Schedule 56, Category 563 27

DLA's ENAC for commercial boilers is "HF."

The UNSPSCs for commercial boilers are 40102001, 40102002, 40102004, 40102005, and 40102007.

Buyer Tips: Make Informed Product Purchases

A boiler system should be capable of meeting the building's peak heating demand and also operate efficiently at part-load conditions. Selecting the right system and properly sizing a boiler requires knowledge of both the peak demand and load profile. If building loads are highly variable, as is common in commercial buildings, designers should consider installing multiple small (modular) boilers in addition to boilers that have modulating burners. In periods of low demand, some of the boilers can be isolated from the other boilers and not incur any standby losses or cycling losses. They can also be automatically staged such that each boiler is running at its most efficient operating point without incurring additional cycling.

For guidance on boiler rightsizing and quality installation, consult the American National Standards Institute/Air Conditioning Contractors of America Standard 5: HVAC Quality Installations Specification (ANSI/ACCA 5 QI 2010).

Federal procurement officers and buyers should consider specifying boilers with the following features:

  • Water temperature reset: Hot water boilers should have the capability for water temperature reset. This is typically based on the outdoor air temperature or the return water temperature. When the heating load is reduced, the supply water is set to a lower temperature.

  • Modulating burners: It is recommended that boilers have the capability to vary their heating output by modulating the burner. Most of the time boilers operate at part load. To prevent excessive cycling and the losses that accompany them, specify boilers that have modulating capability. A minimum turndown ratio of 4:1 is recommended for gas-fired, hot-water boilers. This is particularly important in condensing boilers that run more efficiently at part load.

  • Low mass: Because boilers cycle on and off and it takes time to bring a high-mass boiler up to operating temperature, using low-mass boilers will reduce energy consumption. In addition, some boilers can be brought online quickly, therefore avoiding the need to keep a boiler on hot standby.

  • Remote monitoring capability: Remote monitoring capability is useful to manage boiler operation and to detect any malfunctions in a timely manner.

  • Precise air-fuel ratio control: It is important to keep the air-fuel ratio at optimum levels at part-load operation as well as full-load operation. This is better accomplished by using sensor-driven servos rather than a mechanical linkage (e.g., jack shaft) between the gas input and the blower damper. Oxygen trim systems should be used on larger boilers. Oxygen trim systems monitor the oxygen in the flue gas and adjust the air-fuel ratio for optimum combustion efficiency.

  • Optimum start control: An optimum start control fires up a boiler so that it fires just in time to heat up a building before it is occupied in the morning.

  • Hybrid system: Conventional boilers are more efficient under full-load conditions, while condensing boilers are more efficient under part-load conditions. A hybrid system combines conventional and condensing boilers with controls that operate each type when optimal. This approach can be used in retrofit applications where new condensing boilers are integrated into an existing modular system with conventional boilers. 

  • Other enhancements: Other options to increase efficiency of the heating system include reusing heat from blow down and return condensate for steam boilers, using electronic ignition devices, and increasing boiler and piping insulation.

User Tips: Use Products More Efficiently

Several diagnostic and maintenance procedures are important to maintain efficient boiler operation. Flue gas temperature monitoring is useful in detecting efficiency and operating problems. Maintaining steady excess air levels (with an oxygen trim sensor) ensures that burners will mix air and fuel properly. Low water levels can damage boilers, so water levels should be checked frequently as part of a regular maintenance program. Water treatment can prolong boiler life as well as increase efficiency. Waterside and fireside surfaces should be cleaned annually.

The Boiler Efficiency Institute provides maintenance and operation manuals for boilers and boiler control systems. To encourage quality operations and maintenance, building engineers can also refer to ASHRAE/ACCA Standard 180: Standard Practice for Inspection and Maintenance of Commercial Building HVAC Systems. In addition, the FEMP O&M Best Practices Guide, Release 3.0, Chapter 9 provides valuable information on operation and maintenance of boiler systems.

Lawrence Berkeley National Laboratory provided supporting analysis for this acquisition guidance.