Add motorized dampers to envelope duct penetrations
Building Envelope Duct Penetrations: Motorized Dampers vs. Backdraft Dampers
Motorized dampers that close automatically when an HVAC fan is turned off, saving energy by reducing infiltration.
Item ID: 426
HVAC--Air & Fluid Distribution
Technical Advisory Group: 2010 HVAC TAG (#3)
Historically, mechanical penetrations of the building envelope have been ignored in energy conservation discussions. Building codes have allowed exhaust, intake and relief air penetrations to have no dampers or non-motorized dampers. During off hours, these penetrations allow cold air to blow into the buildings, which triggers heating systems to operate more than needed.
About 10 years ago, these penetrations and their contribution to wasting energy began receiving attention in the energy codes. At that time, larger penetrations were required to have dampers to prevent cold air from blowing into the building when the fans were not on. Currently, most energy codes require motorized dampers on all HVAC penetrations, although some code jurisdictions limit this requirement to penetrations that allow flows of over 300 cfm. Existing buildings are not required to add dampers until they undergo a major system retrofit, so many buildings do not get upgraded.
A combination of incentives and outreach is needed to make decisions makers aware of this energy-saving opportunity. This proposal is to provide such incentives to motivate retrofitting the existing building inventory with motorized dampers on the exhaust, intake and relief air penetrations.
Baseline Description: Typical Commercial Building HVAC
Baseline Energy Use: 10.5 kWh per year per square foot
The 2009 Commercial Building Stock Assessment gives the actual electrical building energy use index (EUI) for various types of heating and cooling systems (Table D-EA5). Office buildings with electric heating and cooling have an EUI of 20.1 kWh/sf/year. Office buildings with no electric heating or cooling use only 8.2 kWh/sf/year, indicating that the combined HVAC heating and cooling energy use is 11.9 kWh/sf/year. For all commercial buildings, the corresponding numbers are 19.9 and 9.4 kWh/sf/year,respectively for a heating and cooling use of 10.5 kWh/sf-year.
Since this technology can be applied to most commercial buildings, a baseline HVAC annual heating and cooling energy use of 10.5 kWh/sf/year is assumed (NEEA, 12/21/2009).
Manufacturer's Energy Savings Claims:
Currently no data available.
Best Estimate of Energy Savings:
"Typical" Savings: 10%
Low and High Energy Savings: 1% to 30%
Energy Savings Reliability: 5 - Comprehensive Analysis
Building leakage studies show about 10% to 15% loss in energy. One of the largest penetrations of the envelope is the louvers. In older buildings, the louvers many not have had any dampers, or if they did, they were neoprene flaps that deteriorate. There are many sources for building leaks, but the louvered penetrations are large compared to cracks around windows and doors.
Energy Use of Emerging Technology:
9.5 kWh per square foot per year
Energy Use of an Emerging Technology is based upon the following algorithm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
Potential number of units replaced by this technology:
This technology applies to existing buildings since codes require dampers for duct penetrations for new construction. The technology also applies to larger buildings with centralized HVAC plants that have duct envelope penetrations. It would not apply to
packaged rooftop units.
Estimates are based on preliminary updated numbers from the 2013 update to the Commercial Building Stock Assessment (CBSA)
Regional Technical Potential:
using the estimates for 2014 ( see Ecotope, Inc., 01/01/2014). Using market shares from the CBSA (see NEEA, 2009) - the percentage of commercial space that is conditioned (85%), and served by chillers and water loop heat pumps (23%) results in: 3,118,000,000 * 0.85 * 0.23 = 609,569,000.
0.64 TWh per year
Regional Technical Potential of an Emerging Technology is calculated as follows:
Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)
Currently no data available.
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.