Zoned Heating and Cooling Can Reduce Energy Use
November 2011
Natural Resources Canada (NRCan) and private sector and academic partners have developed and tested a centrally ducted zoned forced air system that can significantly reduce home energy use while improving comfort.
With a zoned system, the homeowner can use multiple programmable thermostats to specify different temperatures in different zones of the home.
Zoned systems are particularly effective in alleviating comfort issues in multi-storey homes where, on a hot summer day, upper floors are often much hotter than the main floor or basement and, on a cold winter day, the basement is often much cooler than the main or upper floor.
At the same time, zoned systems can be used to reduce overall energy use by targeting the airflow only to the occupied areas of the home.
Optimized Zoned Airflow System Improves Efficiency
larger image
Zoned systems use multiple thermostats to focus heating and cooling to specific areas of the home
The centrally ducted zoned system was tested by NRCan and McMaster University. It was optimized for energy-efficient air delivery by integrating the dampers which direct airflow to different zones in the house with the blower fan in a zoned air-handling unit.
The unit varies fan speeds according to the number of zones calling for heating or cooling based on the multiple thermostat settings. This approach reduces the electrical consumption used for air distribution and can reduce the amount of heating or cooling energy needed.
The system also uses circular zoned ductwork that is sealed against leakage to maximize the efficiency of transporting the air throughout the house.
“This system was field tested in residential housing with boiler-based and hot water tank-based natural gas-fired heat sources and air conditioners,” says Jeremy Sager, who works in NRCan’s CanmetENERGY Ottawa Research Centre. “After a year, houses with the zoned systems had reduced their natural gas use by 7 percent and electrical use by 15 percent, equivalent to a reduction in greenhouse gas emissions of over 300 kilograms per household per year.”
A follow-on study with the Ontario Power Authority, Chatham-Kent Hydro and Kitchener-Wilmot Hydro found that by focusing cooling to only the occupied zones of the house during electrical grid peak times, the centrally ducted zoned system reduced summertime peak electrical use by about 20 percent, while maintaining comfort in these zones. This result indicates that the system could have a significant impact on demand reduction during peak electricity periods.
Expanding the Use of Zoned Systems
larger image
Peak power demand of a zoned forced air system is substantially lower than a conventional system
CanmetENERGY is working in collaboration with manufacturers, installers and software developers to integrate optimized zoned airflow systems with other types of heating, ventilation and air conditioning (HVAC) systems. This includes high efficiency furnaces, air source and ground source heat pumps and even ductless heat pump systems.
Additional work aims to integrate zoned HVAC systems with smart-grid controls. This will link thermostats with time-of-use energy prices to target peak energy savings.
NRCan is also developing guidelines to standardize the installation of zoned systems, making it easier for HVAC manufacturers to successfully launch a zoned version of their product.
For more information on the zoned HVAC system, visit CanmetENERGY’s “Zoned Heating and Cooling Innovation” Web page.
To read about related articles, see Energy Efficiency
For information on reproducing articles, please see our non commercial reproduction section.