If calculation results are available for the base building or improvement package, the following verifications are performed:

  1. A Package does not save more than 50% of the energy used by the Base Building.
  2. The heating system is not undersized. If the heat plant is undersized, then the living space will be cooler than the thermostat set point temperature during cold weather, and energy usage of the building will be underestimated. For detailed information on heating load view the Design Heating and Cooling Loads Report.
  3. The heat plant output exceeds the building load by the safety factor specified on Load Sizing screen. This will not affect modeling results. Since heating systems are usually sized conservatively, this may serve as a warning that building heat loss or heating system losses are overestimated.
  4. The heat plant output adjusted for the safety factor does not exceed the building load by more than 50%. If it does, it may indicate that building heat loss or heating system loss is underestimated – for example not all surfaces/windows have been entered, useful heat loss from heating /DHW system/appliances is overestimated, infiltration is underestimated, heating/distribution efficiency is overestimated, etc.
  5. Heating distribution system efficiency is at least 60% for primary and secondary distribution systems, which is typical for residential applications. It is also important to check that estimated distribution efficiency entered in distribution window of Heating/Cooling screen does not differ significantly from calculated distribution efficiency shown on Design Heating/Cooling Load report. If the difference is large, enter estimated distribution efficiency equal to calculated distribution efficiency and recalculate the project.
  6. The heating reference temperature is at least 50 F. If the outdoor temperature is below 50 F, a typical residential building should require heating.
  7. The cooling reference temperature is at least 70 F. Typical residential buildings should not require cooling if the outdoor temperature is below 70 F.
  8. Calculated heating slope is in the typical range. It usually varies from 2 Btu/HDD-SqFt for best new construction to 25 Btu/HDD-SqFt for high usage existing home. Note that the limits may be different for your housing type.
  9. At least 500 HDD or CDD were used to calculate the Heating/Cooling slope. Heating/Cooling Slope may not be accurate if actual HDD/CDD are low since actual weather data in not available on hourly basis.
  10. Cooled spaces can usually take advantage of free cooling provided by natural ventilation, which may be entered on the Advanced window of the Spaces screen. Natural ventilation is modeled only during the months that are not part of the heating season. Heating and cooling seasons are entered on the Weather/Defaults screen.
  11. A table is displayed with the calculated average monthly temperatures of each unconditioned space. The temperature depends on the heat transfer through exterior surfaces, heat exchange with adjacent heated spaces, internal gains from lighting and appliances. It does not account for internal gains from heating or DHW systems, if any. Make sure that the temperatures are close to the ones measured during the site visit.