Energy Efficiency Experts

Delta Q Duct testing.

Delta Q was developed by the Lawrence Berkeley Labs. It uses a blower door to test duct leakage. The blower door is set for four separate ten point tests. The blower door is set up and the house is winterized as in any blower door test.  We test for the CFM leakage as we normally do during a blower door test.

Then is scaled down in pressure is scaled down at ten different points.

For example we start with pressurization at 50 Pascal's. We then move to 42. Then to 35. Etc until we have ten measured points moving down a scale.

We run this test four times in the following requirements.

Depressurization with the Air Handler off (heater or ac or HVAC fan) at ten scaled down points

Depressurization with the Air Handler on ten scaled down points

Pressurization with the Air Handler off scaled down at ten different points

Pressurization with the air handler on a ten different scaled down points.

This data is then plugged into the Delta Q formula developed by LBL and it produces the results.

What is really cool is it gives the data in two different forms. It measures the return side leakage(air returning to the HVAC unit) and the supply side leakage(air coming into the room from registers).

I wont pretend to understand the whole aspect of it nor will I attempt to explain in detail. I have provided the link to the experts. I am simply standing on the shoulder of those before me and providing the service to my customer base.

What I like about it is the ability to test systems and have data that points us in the direction of the worst problem areas. It is also useful in existing homes where wall cavities have been used for return air. In these instances the duct blaster tells us only part of the story.

It should be noted Delta Q is not accepted for HERS testing in California at this time