Analyzing Design Heating Loads in Superinsulated Buildings

Timothy Merrigan, L. Arena

Research output: NRELSubcontract Report


Designing a super insulated home has many benefits including improved comfort, reduced exterior noise penetration, lower energy bills, and the ability to withstand power and fuel outages under much more comfortable conditions than a typical home. Extremely low heating and cooling loads equate to much smaller HVAC equipment than conventionally required. Sizing the mechanical system to these much lower loads reduces first costs and the size of the distribution system needed. While these homes aren't necessarily constructed with excessive mass in the form of concrete floors and walls, the amount of insulation and the increase in the thickness of the building envelope can lead to a mass effect, resulting in the structures ability to store much more heat than a code built home. This results in a very low thermal inertia making the building much less sensitive to drastic temperature swings thereby decreasing the peak heating load demand. Alternative methods that take this inertia into account along with solar and internal gains result in smaller more appropriate design loads than those calculated using Manual J version 8. During the winter of 2013/2014, CARB monitored the energy use of three homes in climate zone 6 in an attempt to evaluate the accuracy of two different mechanical system sizing methods for low load homes. Based on the results, it is recommended that internal and solar gains be included and some credit for thermal inertia be used in sizing calculations for super insulated homes.
Original languageAmerican English
Number of pages43
StatePublished - 2015

Bibliographical note

Work performed by Consortium for Advanced Residential Buildings, Norwalk, Connecticut

NREL Publication Number

  • NREL/SR-5500-64236

Other Report Number

  • DOE/GO-102015-4673


  • Building America
  • CARB
  • climate zone 6
  • design heat load
  • low load
  • manual J8
  • passive house
  • residential
  • Residential Buildings
  • super-insulated


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