Office Outside Air Economizers

Spend $1,000 now and SAVE $278 each year... ROI = 27.8%

Many commercial HVAC systems have an economizer feature. This brings in outside air for cooling when it’s cooler than the air inside. Since many offices do not have operable windows, this is the next best alternative. Economizers save energy, which is important as Heating, Ventilation, and Air Conditioning account for 49% of an office's annual energy costs, but more importantly for your empolyees, it will bring more fresh air inside. The climates that are ideal for economizers are the ones that have summer nighttime temperatures that drop down relative to the daytime temperatures. It’s often cool enough outside that an economizer can effectively be used frequently.

The savings from this “free cooling” can be big. Some HVAC systems enable this function very easily. Even when you have to add more equipment and controls, an economizer will pay for itself on average in three and half years. Some properties may see a payback in as few as two years while other climate conditions may take up to five years for a payback. Economizers can be used to pre-cool the building for additional energy savings.

A nighttime building “flush” works well in larger offices that don’t really cool down overnight. An hour or two of fresh outside air in the early morning provides additional free cooling. Even over the summer, the temperature across a good portion of America drops into the 60’s or 70’s at night. Nighttime pre-cooling can mean the office is cool and comfortable when people arrive for work instead of hot and stuffy. That could help make your employees more productive. At the same time, you’ll save by not having to run your air conditioning as much during the day. This tactic works similar to an Office Whole Building Fan.

The ROI Calculation is based on the US average ten person office which generates $278 of cost per employee for a total annual HVAC cost of $2,785 for a 2,500 sq. ft. office. An outside Air Economizer that costs about $1,000 may produce an average savings of 10% leading to annual energy savings of $278 for the ten person office. In climates that have a steeper drop off temperature at night, the savings will increase as it also will for offices that have more employees that work within the same HVAC system.

Time in
5 Year
Return on
3.5 $1,000 $278 $1,390 27.8%


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