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Serving King County and Snohomish County

Serving King County and Snohomish County


Evergreen State Heat & AC Blog

Why Rooftop HVAC Units Are the Norm


Here’s a question we sometimes hear from people who are curious about the differences between residential comfort and commercial comfort: “Why are the HVAC systems usually up on the roof of a building?” People aren’t used to seeing HVAC equipment on the roofs of houses after all. 

Rooftop HVAC units, which are the most popular type of air conditioning and heating system for commercial buildings, are systems we’re familiar with: we install, repair, replace, and maintain them, and we can tell you about why they’re placed where they are. It involves a bit of history of the development of both business and HVAC technology.

Downtown Development Before Modern HVAC

Before the easy availability of cars and long-distance transit, businesses were centered in downtown areas of cities. Here buildings were placed close together to compress space and make it easier for people to move around and reach places without long trips. These buildings were made before the development of refrigerant-based systems and did not have ACs, instead relying on simple furnaces or boilers in the basement that let heat rise naturally up through pipes and ducts. 

When the commercial air conditioning and heat pumps became available, they needed outdoor space for exhaust so heat could be moved out of or into the building. There wasn’t enough space around the building for this (and there was also concern about vandalism), so the units had to be placed up on the roof.

The Other Benefits

As the suburbs spread and businesses found roomier places aside from crowded downtown areas, HVAC units still mostly stayed up on roofs, although there are exceptions. The reasons for this is that the rooftop locations ended up offering other benefits for a commercial building:

  • Equipment protection: We already mentioned that putting valuable equipment on the roof was much safer than on the ground, where vandalism could easily damage it. 
  • Aesthetics: HVAC equipment isn’t exactly pleasing to look at. Trying to disguise the equipment on the ground (as well as wall it off or fence it in to protect it) was much more work than simply keeping it out of sight on the roof.
  • Less noise pollution: Rooftop units create less noise for the business as well as the world outside.
  • Ease of access for technicians: It’s simple for technicians to repair and maintain equipment that is moved out of the way of the business itself. Just a trip to the roof and they never may even need to step foot inside the business. 
  • Modular: Most rooftop HVAC units are modular and can expand as the needs of a business do. Rooftops provide easy space for this modular expansion.
  • Better settings for action movies: What would action shoot-outs on roofs be like if the stunt performers didn’t have HVAC equipment to duck behind? Yes, this probably won’t have a big effect on your business, but it’s something we wanted to point out. 

We’re the contractor to take care of your needs in Everett, WA, for commercial heating and cooling. We’ll handle any repair, maintenance, or installations you need for rooftop HVAC units.

Evergreen State Heat & AC serves Snohomish County & The Eastside. Reach out to us for 24/7 on-call dispatching.

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