Energy-efficient space heaters deliver green plants and profits

Heating industrial buildings is a bigger challenge than ever before. Companies need to save energy, improve indoor air quality and get “greener” by reducing their building's carbon emissions footprint.

By Ken Williams, Cambridge Engineering Inc. March 1, 2009

Heating industrial buildings is now a bigger challenge than ever before. Companies need to save energy, improve indoor air quality and get “greener” by reducing their building’s carbon emissions footprint. This is especially true for heating industrial facilities that require ventilation, where often the greatest energy savings can be achieved.

The nice thing about saving energy is that it lowers operating costs and reduces air pollution. Current high-efficiency space heating technologies, such as direct-fired blow-through heaters, can provide up to 70% energy savings. To put this in perspective, just a 50% energy savings from more efficient industrial space heaters saves $937,500 over 10 years at a 500,000 square-foot Chicago warehouse using conventional indirect gas-fired heaters.

It’s easy to see why energy efficient space heating equipment pays for itself. The same 50% energy savings also reduces the building’s annual carbon footprint by 440 tons of CO 2 . This is equivalent to planting 13,200 new trees during the next 10 years.

Energy efficiency for industrial buildings should not mean sacrificing the ability to provide enough space heat or ventilation when and where you need it.

Studies show making this mistake can ultimately result in more energy use and lower employee productivity. Heating a warehouse, service center, assembly area or manufacturing plant requires careful consideration of some unique factors, including cold dock door areas, heat stratification, ineffective spot heating, not accounting for required tempered make-up air or using an undersized system that fails to heat the building on a cold day. These problems can be addressed by using some best practices.

A best practices guide to space heating

  • Use 90% efficient heaters — ASHRAE guidelines reference three different types of gas-fired heater efficiencies based on the size and type of heating equipment: Ec (Combustion Efficiency), Et (Thermal Efficiency) and AFUE (Annual Fuel Utilization Efficiency). Select space heaters with energy efficiency ratings above 90% to get every possible Btu out of the fuel as useable heat.

  • Consider ventilation and IAQ — Be sure the heating system accounts for the facility’s ventilation and indoor air quality requirements. For example, indirect gas-fired boilers, unit heaters and air rotation systems that only heat recirculated indoor air provide no building ventilation. The same is true for infrared heating systems, which have no blowers and provide no ventilation. When a mechanical exhaust system is used, the building can be starved for make-up air. The use of direct gas-fired heating equipment can be an energy- efficient solution for these problems.

  • Reduce stratification — Reduce temperature stratification in buildings with high ceilings. Heating systems that provide significant air movement will both reduce stratification and provide more uniform temperatures throughout the building. Large, low-velocity constant air rotation heating units that provide two to three building air-volume turnovers per hour are one solution, but this comes at the expense of higher electrical usage for larger horsepower blower motors.

  • Be ASHRAE 90.1 compliant — Heating equipment should, at a minimum, be compliant with ASHRAE Energy Building Standard 90.1. This does not necessarily ensure you are getting the most energy-efficient heating equipment. But it is a requirement for many government tax incentives and utility rebate programs. It is also a prerequisite for LEED green buildings. The heater manufacturer should have this stamped on their nameplate.

  • Document energy savings — Since actual energy savings are the real goal, use a proven technology from an experienced manufacturer that can document energy savings with studies of existing buildings and energy modeling.

    • Warehouse size Annual energy savings 10-year dollar savings Annual reduced CO 2 emissions4(tons) 10-year impact on environment5
      Source: Cambridge Engineering Inc.
      50,000 7,500 $93,750 44 1,320
      100,000 15,000 $187,500 88 2,640
      500,000 75,000 $937,500 440 13,200
      1,000,000 150,000 $1,875,000 880 26,400
      4Therm = 11.7 pounds of CO 2 5Equivalent numbers of trees planted according to American Forests tree calculator

      Other industrial heating systems Energy savings with blow-through space heaters
      Indirect gas-fired systems
      Boilers 53%
      Unit heaters 51%
      Air-turnover systems 33%
      Infrared (radiant) 59%
      Direct gas-fired systems
      Make-up air 24%
      Recirculation (pressurization) 28%
      Author Information
      Ken Williams serves as director of marketing for Chesterfield, MO-based Cambridge Engineering Inc. He can be reached at (800) 899-1989 or e-mail .