There Are Holes in Our Walls

A graphic showing a window air conditioner installed in a window with accordian sleeves.

Research conducted by Steven Winter Associates and Urban Green Council, funded by NYSERDA

Key Takeaways

  • AC units can leak excessively, as much as a six square inch hole in the wall
  • Inexpensive solutions can easily be handled by in-house building staff

Executive Summary

This study examines the impact on thermal performance of building envelope penetrations associated with distributed heating, ventilating, and air conditioning (HVAC) equipment such as window air conditioners (ACs), sleeved ACs, and packaged terminal air conditioners and heat pumps (PTACs and PTHPs). Physical testing of sixteen different AC and PTAC units in eleven buildings revealed that the infiltration losses through leaks and poorly-fitting installations are far greater than might be expected. The associated heating losses are estimated to cost about $150 million per year in excess fuel use and result in the emission of around 400,000 tons of CO2 annually – about 1% of the city’s annual total. The research was performed by Steven Winter Associates and made possible by Urban Green Council.

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