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Green Building Blog

Unexpected Benefits of “Greening” Your Building’s HVAC System

Thu, Jul 10, 2014 @ 01:53 / by Jim Newman

If reducing your utility bills is the goal - smaller, more efficient equipment is one way to get there.

The obvious reason to “green” or improve the energy efficiency of a commercial or industrial building, school or hospital is to reduce operating costs. It makes sense that the less energy the HVAC system uses, the less money it will cost, and the lower the utility bill will be.

But “Greening” is not only about heating and cooling the building with less energy.  Simply installing that higher efficiency chiller, boiler or rooftop unit is only one step.  

Consider also what size chiller or boiler the building actually needs. By first reducing the overall energy load, a smaller, and perhaps even more energy efficient unit, may suffice. This will increase energy efficiency savings exponentially. “The least expensive unit of energy is the one you never use.”

This is true whether you are considering new, smaller equipment, or a more forward-thinking plan like incorporating renewable energy, such as geothermal, wind or solar. (Read more about making the solar investment work for you here.) And be sure to work with a qualified engineer who knows how to size the proper equipment, not just for the building, but for the actual load.

The key aspect, whether designing a new building or retro-fitting an existing one, is to integrate the mechanical and electrical systems so they work with the design of the building envelope. This may mean making adjustments to the building envelope, an investment that will pay off in the long run. Those adjustments may include:

  • Additional/different insulation in walls and roof for higher R-value (lower U-value)
  • Different type of roof membrane
  • Vegetated roof
  • Roof overhangs
  • Better window treatments, e.g., exterior shading, window film or interior storm windows (especially for historic buildings so that existing windows can remain as is)
  • Less actual fenestration (ASHRAE Energy Standard 90.1-2010 states that “the total vertical fenestration area shall be less than 40% of the gross wall area” in section IECC-2012, which has been adopted by a number of jurisdictions, refers to Std. 90.1-2010.)
  • Light shelves to bring daylight further into the building
  • Skylights and/or light tubes
  • Better air barrier design

Note: see ASHRAE Energy Standard 90.1, Section 5 and User Manual for more information.

In addition, when reducing the size of major mechanical equipment, such as chillers and boilers, the size of all the ancillary equipment also becomes smaller - something many people don’t think about. The volume of water being used, the pumps, the fans, the starters and electrical wiring, the piping and insulation, and often the labor hours all are also reduced. This makes a considerable difference in first cost as well as in lower energy costs that will continue throughout the life of the building.

There’s no doubt that reducing energy use is an important issue.  In a recent survey more than 1300 building owners, chief executives, vice presidents and facility managers from various major industries all over the world responded.

• 72% said they are paying more attention to energy efficiency than last year (up from 60% in 2011)

• 41% said that energy management is extremely important to their company

2013 Energy Efficiency Indicator (EEI) Survey (IFMA and Johnson Controls)

So what do you do when you want to improve the energy efficiency of a building?

For starters, don’t do the so-called “easy fixes,” or “low-hanging fruit.” If you do, you may sabotage your ability to get the needed funds for equipment replacement. See more about easy HVAC fixes here.  Also, if you can increase the R-value of the building envelope even before purchasing the new equipment you can improve your results significantly. Read about the results of the extensive but financially worthwhile Empire State Building retrofit.  

But now you have to pay for it. How do you convince the people who are paying the bill? You need to show them the numbers – all of them. The best and most verifiable way to get accurate numbers is through an ASHRAE Level II Energy Audit or the new ASHRAE Building Energy Quotient labeling program (bEQ). A qualified energy professional will pay for themselves in the energy savings you will realize over the short and long term.

And that’s being green all the way around. 

Topics: HVAC, Commercial Building, bEQ, solar, Building Energy Quotient, Green, ASHRAE, Green Building, energy efficiency, Energy Savings, Energy Audit

Jim Newman

Written by Jim Newman

Jim Newman's passion is helping us move toward a healthier and more secure future – for people and the planet.

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