You can use the following methods to compute the annual energy savings from duct weatherization:
- Approved energy modeling software to know the modeled energy savings. This uses complex algorithms to determine how duct weatherization will contact with other energy efficiency measures taken in a home, and what would be their impact on energy savings.
- You can use the below formulas below to compute energy savings from duct weatherization.
Annual Energy Saving Algorithms:
Compute the Distribution Efficiency by assessing duct system before and after duct sealing using Building Performance Institute “Distribution Efficiency Look-Up Table”
Cooling savings from reduction in Air Conditioning Load:
ΔkWh cooling = ((((DEafter – DEbefore)/ DEafter)) * FLHcool * BtuH) / 1,000 / ηCool
Where:
- DEafter = Distribution Efficiency after duct sealing
- DEbefore = Distribution Efficiency before duct sealing
- FLHcool = Full Load Cooling Hours*
- BtuH = Size of equipment in Btuh (note 1 ton = 12,000Btuh)
- ηCool = Efficiency in SEER of Air Conditioning equipment= actual. If not available use:
Heating savings for homes with electric heat (Heat Pump of resistance):
kWh = (((((DEafter – DEbefore)/ DEafter)) * FLHheat * BtuH ) / 1,000,000 / ηHeat ) * 293.1
Where:
- FLHheat = Full Load Heating Hours**
- BtuH = Size of equipment in Btuh (note 1 ton = 12,000Btuh)
- ηHeat = Efficiency in COP of Heating equipment (HSPF)
For homes with Fossil Fuel Heating:
ΔMMBTUfossil fuel = ((((DEafter – DEbefore)/ DEafter)) * FLHheat * BtuH ) / 1,000,000 / ηHeat
Where:
- DEafter = Distribution Efficiency after duct sealing
- DEbefore = Distribution Efficiency before duct sealing
- FLHheat = Full Load Heating Hours**
- BtuH = Capacity of Heating System
- ηHeat = Efficiency of Heating equipment
The MA TRM sets 360 hours as the full load cooling hours for MA and 1200 heating hours as the full load heating hours for MA.