First of all, if you are not familiar with HVAC Zoning (Zone control) for your home you can click here and learn more about how it works.
Sometimes, zoning is pitched as a device that can be added to your current HVAC system that will "save you energy" because you are able to turn "off" heating and cooling to areas that are not being used. Sounds good, right? Well...there a "but." This as actually a highly debated or more aptly put... highly contested claim among HVAC professionals.
The simple fact is that it isn't a simple answer but the simplest version is: HVAC Zoning CAN save energy in some applications.
Not all applications of zoning are intended to save energy, some are set up to optimize comfort. In these situations, energy savings may not the top priority but it can still be set up to help save energy when the comfort is not in demand.
Zoning puts the control in the hands of the user (homeowner) via the thermostats. These thermostats can be set to optimize energy savings or comfort... or, most likely, somewhere in between.
Some believe the primary purpose of zoning is comfort & I would agree, but, SmartZone can be used in some applications to save energy by reducing necessary run-time.
As far as I have found there have been very few and NO independent studies on the energy savings capabilities of hvac zone control but I have personally been in the industry for 14 years and I believe I know why. Every test I have seen is try to prove some % of energy savings and yet there is a flaw with even the question that is being asked. The problem with this question is that it is looking for an automatic percentage saving when zoning is installed. I think this gets to the heart of why the professionals that dispute zone control's ability to "save energy" do so.
This is an IMPORTANT NOTE: HVAC Zone Control by itself will NOT save energy. However, it CAN be used to save energy.
A proper study to prove that zone control CAN save energy would be straight-forward. Two identical houses with identical hvac systems, one with a 2 zone system & the other with a single thermostat. On the house with zoning, set one thermostat to OFF 12 hours per day and the other thermostat to run a normal 24hr / 7 day schedule. The thermostat schedule should be the same as the 24hr / 7 day schedule in the house with only one thermostat. This study would show that zoning can save energy if used in certain ways.
SmartZone has been around since 2004 and we have over 200,000 installed in the field. We have seen direct feedback that empirically shows energy savings, not just in isolated cases but in extremely high volume. First hand, real-world experience shows that it can be done, but it also shows that in cases where comfort is the priority... energy savings isn't a guarantee with zone control.
Check out SmartZone at ZoningSupply.com