Going Green with HVAC

  • The number one reason for the green movement within the residential housing industry should be energy conservation.  And what is the #1 way to green up your home?  It’s not by selecting low or no VOC paints and finishes.  And it’s not by using bamboo instead of wood.  CFL’s (compact fluorescent lamps) are a good idea but that isn’t #1 either.  The best way to go green is to make sure your heating and air-conditioning are working as efficiently as you can make them.  Because if your HVAC system isn’t at peak integrity, then you’re negating all the other green steps you’ve taken in your home. HVAC is an acronym for heating, ventilation, and air conditioning.  Generally along the Gulf Coast heating isn’t as much of a concern as air-conditioning.  After all, it’s conceivable we could run our air conditioning 12 months out of the year during a mild winter.

    How does one go about greening up your HVAC system?

    1. What is the overall efficiency of your entire system?  The efficiency of air conditioners is rated as the Seasonal Energy Efficiency Ratio (SEER).  The higher the SEER on an air conditioning unit, the more efficient it is.  Central air conditioning units manufactured after 2005 must be a 13 SEER or higher.  ENERGY STAR qualified units must be 14 SEER or better.

    2. Is ductwork properly sealed and designed properly? Ductwork is located in the attic and walls and in between the floors of a multi-story house.  These areas are usually not insulated and if the ductwork isn’t properly sealed the conditioned air will leak into the unconditioned areas. Ductwork can be pressure tested for leaks that aren’t obvious or in inaccessible areas.  Leaks in ducts should be sealed with a special kind of air-conditioning tape, not duct tape.  And ductwork should be as straight as possible.  For every turn in the duct, drag is created in the airflow reducing the efficiency.

    3. Is ductwork contained in an extremely hot or cold unconditioned attic? Its not unrealistic that in an unventilated attic, temperatures can reach in excess of 140 degrees on some summer days when the outside temp might only be 95.  So it makes sense if you lower the attic temperature, that extreme heat doesn’t have a chance to raise the temp of the air pulsing through the ducts in your attic.  How do you do that?  One way is to create a basic push pull system of air exchange in the attic.   The cooler 95 degree air is pulled into the attic through soffit or ridge vents and the hotter 140 degree air leaves the attic pushed out by ventilation fans or roof turbines. Another way to cool the attic is to apply a radiant barrier to the underside of the roof reflecting the heat out of the attic.  The best way to install a radiant barrier in a preexisting home is to have a special radiant paint sprayed on the underside of the roof.  This is not a DIY project.  A professional should install it. A foil radiant barrier should be installed standard in new homes.

    4. And fourth, is your filtration system clean?  In order for a system to work efficiently it must receive intake air as a balance to the air it is producing.  That air comes from inside your house through your filter.  The filter of a system should be changed or cleaned every month.  If you’ve got a dirty filter, you’re reducing the amount of air to the unit and recycling that dirt back into your HVAC equipment.  You’re running the risk of the condenser freezing up because it isn’t getting enough air and or the pan stopping up from the extra dirt.  If either happens, your air conditioning stops cooling and you get hot.

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