Makeup Air In Energy Star Home

[Rich Goeken]

Not sure where to look in the codes for this one.

As you know, Energy Star Homes are tested to insure that they are tight and do not allow infiltration of outside air or the escape of conditioned air to the outside.

This leads to the problem of makeup air for the bathroom fans and the range hood (if it exhausts outside the structure). Because of the tightness of the home, a small fresh air intake (example, 4") may be provided in the HVAC system, but is usually system controlled and may be off when the system is not functioning.

I know makeup air should be provided in the laundry room if combustion is present, but not required if the appliances are electric.

I am stumped trying to find the applicable requirements or if this issue is even addressed in the codes. Comments would be appreciated.

[Raymond Wand]

Building Science
http://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/ENERGY_STAR_V3_Building_Science.pdf

[Robert Ernst]

For Energy Star V3 ventilation is addressed in the standards. It's the ASHRAE 62.2 2010 standards. The IRC addresses combustion air and AHSRAE addresses the size of exhaust fans allowed.

If someone is building a new Energy Star home and putting combustion appliances indoors that are not sealed combustion I would be surprised. They might have a separate closet that has vents to the exterior and a door with a gasket to seal it off from the conditioned space.

[Jerry Peck]

Not sure where to look in the codes for this one.

As you know, Energy Star Homes are tested to insure that they are tight and do not allow infiltration of outside air or the escape of conditioned air to the outside.

This leads to the problem of makeup air for the bathroom fans and the range hood (if it exhausts outside the structure). Because of the tightness of the home, a small fresh air intake (example, 4") may be provided in the HVAC system, but is usually system controlled and may be off when the system is not functioning.

I know makeup air should be provided in the laundry room if combustion is present, but not required if the appliances are electric.

I am stumped trying to find the applicable requirements or if this issue is even addressed in the codes. Comments would be appreciated.

You won't find those in the codes ... the codes are "minimum" documents and the Energy Star stuff is an "above code" program, with the key being "above" code (i.e., not addressed in the minimum codes). ;)

[Rich Goeken]

You won't find those in the codes ... the codes are "minimum" documents and the Energy Star stuff is an "above code" program, with the key being "above" code (i.e., not addressed in the minimum codes). ;)

Then how would you achieve the required air changes in a bathroom in a tight house such as an Energy Star Home?
I hope that you are not saying that programs such as this are running hell bent on election down the road without considering their effect on a home, its occupants, and the codes.:)

[Raymond Wand]

Ideally you need a balanced system, equal air in and equal air out.

[Robert Ernst]

Then how would you achieve the required air changes in a bathroom in a tight house such as an Energy Star Home?
I hope that you are not saying that programs such as this are running hell bent on election down the road without considering their effect on a home, its occupants, and the codes.:)

I believe what he is saying is that Energy Star is a voluntary certification of a home. It is not a code. It is actually about 15% better than the IECC requirements. Many of the requirements in Energy Star home end up being code one day that's why you see the versions update. If you read my previous post there are codes and standards that address air changes as well as fan flows.

[Rich Goeken]

Not sure where to look in the codes for this one.As you know, Energy Star Homes are tested to insure that they are tight and do not allow infiltration of outside air or the escape of conditioned air to the outside. This leads to the problem of makeup air for the bathroom fans and the range hood (if it exhausts outside the structure). Because of the tightness of the home, a small fresh air intake (example, 4") may be provided in the HVAC system, but is usually system controlled and may be off when the system is not functioning. I know makeup air should be provided in the laundry room if combustion is present, but not required if the appliances are electric.I am stumped trying to find the applicable requirements or if this issue is even addressed in the codes. Comments would be appreciated.

I received the following response from the Energy Star Folks.....

There are no specific requirements in the ENERGY STAR Certified Homes, Version 3 (Rev. 06) program requirements that specify the method by which the home is supplied makeup air. As you alluded to, the air would typically be provided via the path of least resistance through the envelope, the exception being if the home has “balanced” type whole house mechanical ventilation, such as an Energy Recovery Ventilator, Heat Recovery Ventilator, or a system which has a control system linking exhaust fans with a supply fan or an inlet damper.

The ENERGY STAR Certified Homes program aligns with ASHRAE 62.2-2010 on almost all issues related to indoor air quality and ventilation. When you are performing the air flow tests associated with Section 8 of the HVAC System QI Rater Checklist (HVAC-R) (Rev. 06) and find that you are not able to attain the required air flows with a fan that has been rated at that air flow, you may add your own air intake to help balance the system if it complies with ASHRAE 62.2-2010 and Section 7 of the HVAC-R. We have heard of partners installing fans with rated air flows higher than those required in Section 8 of the HVAC-R to ensure that enough air flow will be delivered. Section 7 outlines the location requirements for ventilation air inlets to ensure known contaminants are not being brought into the home.

We have not heard of any durability concerns associated with the installation of supply side or exhaust ventilation systems that are not linked to one another. I would also like to note that the fresh air intake on the supply side of your HVAC system is not, by itself, an ASHRAE 62.2-2010 compliant whole house mechanical ventilation strategy unless it is set to run at a minimum specified interval when the HVAC system itself is not running. For example, in shoulder seasons when there is no heating or cooling load on the house, there must still be a way to supply continuous or intermittent whole house mechanical ventilation."

[Bob Harper]

ASHRAE 62.2 calls for a min. of 0.35 air changes per hour, which is ASSumed to provide sufficient minimal infiltration to support low flow exhaust fans such as bathroom vents and clothes dryers. A kitchen exhaust hood >450cfm requires its own interlocked MUA source.

Note these stds don't forbid ANY infiltration or exfiltration--they try to LIMIT it within guidelines.

[Nick Ostrowski]

So to apply this to my thread http://www.inspectionnews.net/home_inspection/heating-ventilation-air-conditioning-hvac-home-inspection-commercial-inspection/34352-furnace-pulling-return-air-attic.html, there is no code prohibiting pulling return air from the attic space?

[Scott Patterson]

So to apply this to my thread http://www.inspectionnews.net/home_inspection/heating-ventilation-air-conditioning-hvac-home-inspection-commercial-inspection/34352-furnace-pulling-return-air-attic.html, there is no code prohibiting pulling return air from the attic space?

You can not mix conditioned air with unconditioned air.... The common sense code!!

[Rich Goeken]

You can not mix conditioned air with unconditioned air.... The common sense code!!
You do that now in the Energy Star system. Prior energy Star it was done using various devices to extract heat or cold from the exhaust air to heat or cool the incoming air, or unconditioned was just ducted it into the plenum. If you follow the code for replacement of combustion air in a laundry room, you are bringing unconditioned air into a conditioned space. Splain please.

[Scott Patterson]

You do that now in the Energy Star system. Prior energy Star it was done using various devices to extract heat or cold from the exhaust air to heat or cool the incoming air, or unconditioned was just ducted it into the plenum. If you follow the code for replacement of combustion air in a laundry room, you are bringing unconditioned air into a conditioned space. Splain please.

OK I will try...

When a "High-Low" combustion air system is added to increase the make-up air in a room that has fossil fuel burning appliances the air is not being introduced into the conditioned airstream. The return air as well as the supply is suppose to be a sealed delivery system with no leaks or holes in it. This is why when you have a damaged heat exchanger CO can and is often introduced into the living space of a home.

Eventually the make-up air from the attic will become conditioned air as it mixes with the air in the living space and is drawn back into the return air where it will pass through a filter and the coil becoming conditioned.