General Information

When installing a new heating or air conditioning system in a historic building, make sure it is a good fit with the building as well as with your needs. Ask questions to ensure you are getting exactly what you need and want.

Be clear about what you want and what your priorities are.

Each house is unique and has different needs:

  • ♦  Are the walls, attic, and crawlspace well insulated?
  • ♦  What is the square footage/capacity?
  • ♦  Is the airflow properly set up?
  • ♦  How much space is in the walls and between floors for ductwork if using standard duct system?

General rules of thumb are not the best answer for a historic structure:

  • ♦  A full study should be done that includes floor plan drawings, wall space, and existing ventilation.
  • ♦  Must consider:
    • ◊  Use of the space
    • ◊  Humidification
    • ◊  Air purification (optional)
    • ◊  Placement
      • −  Supply, register, and return air vents
      • −  Thermostat locations
  • ♦  This isn’t an estimate. It is a study.

Priorities: What is most important to you?

  • ♦  Price?
  • ♦  The aesthetics of how heating and cooling enters a room?
  • ♦  Keeping the temperature at a certain level? 65 – 70 – 75 degrees?

There is a balance to the HVAC system in each building. Remove an intake, vent, or radiator and it will affect the whole system.

  • ♦  Additions or removal of walls may have been done without these things considered. Another reason for a full assessment before starting the project.

If you have radiator heat in your home—KEEP IT!

  • ♦  Very efficient and can be run at a lower cost than most other heating systems when all factors are considered.
  • ♦  Do a study to determine what will actually save money before making changes. Will insulation cost less in the long run?

Reducing the Impact on Your Historic Home

If you are installing a new heating system or adding air conditioning, how can it be done without negatively affecting your historic home?

  • ♦  Is there room for large ductwork in your walls? If not some options:
    • ◊  Ductless heating and cooling systems
      • −  Also referred to as mini-split, multi-split, or variable refrigerant flow (VRF) heat pump systems.
      • −  May not aesthetically match a historic interior—consider location carefully.
    • ◊  High velocity systems take up less room in walls and ceilings.
      • −  Be sure to hire someone very experienced with the system.
      • −  If not designed and installed correctly, it will not work efficiently.
  • ♦  Historic Integrity
    • ◊  Minimize the intrusion of HVAC equipment and ductwork through careful placement in less historically significant areas of the structure. (Closets and basements can be convenient places for HVAC components without damaging more historically significant areas the structure.)
  • ♦  Price Considerations
    • ◊  Geothermal
      • −  Good sustainable option, low monthly cost after a large initial investment.
      • −  Still requires installation of ductwork and mechanicals, as well as maintenance to keep system in optimal operation.
      • −  Ground geology impacts installation
    • ◊  There are a variety of price levels in heating and cooling equipment, and they are complex electronic systems. Be aware of this if using price as your deciding factor.


Have your system serviced regularly to ensure there is proper:

  • ♦  Air flow
  • ♦  Charge
  • ♦  Voltage

Semi-annual service and cleaning of your system (or annually if only used for heating) will keep it working properly and could save you money in emergency repairs or operating costs.

  • ♦  Most HVAC contractors provide discounted services and repairs to customers participating in a regular maintenance plan.


Preservation Brief 24—Heating, Venting, and Cooling Historic Buildings by Sharon C. Park, AIA

Air Conditioning Contractors of America—Homeowner Resources

American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE)—Publications and technical information on HVAC in historic buildings

Energy Efficiency: Mechanical Systems—Common Sense Preservation