# Vented Attic/HVAC Improvement help



## bmwstephen (Jun 17, 2019)

Hi all-



Recently purchased a new construction in Northern California that touts energy efficient practices and exceeding code. Although it had all the superficial features that tout that (Solar, Tankless Water, Bibs insulation, rigid foam exterior insulation, and drought resistant plants)... I was extremely underwhelmed by the attic and HVAC design.... Here are the specs:



-vented attic in a complex roof; venting via soffit vents

-radiant barrier

-r30 underneath loose blanketed fiberglass

-HVAC unit housed in attic

-all flex ducting throughout the hose (2 story)

-whole house fan (sucks hot air and disperses it into the attic)



My concern is that we experience 100+ degree days ere which would mean 160+ in the attic itself. That could cause some added wear to the HVAC equipment.





Does anyone have any recommendations on what to do such as turn it into a conditioned space?


----------



## Bud9051 (Nov 11, 2015)

You are correct to be concerned about the hvac equipment being in the unconditioned attic. Not a good choice and when done there are air leakage and insulation requirements. We rarely see equipment in the attic here in Maine as most houses start with a full basement just to get below the frost line.

Did they provide any documentation on energy testing, like house and duct air leakage?

An attic can be converter from vented to unvented but that would involve moving the insulation layer to the roof plane. The reality is, the penalty you are paying probably doesn't justify the cost to do that.

Are your heating or cooling bills extreme?

Bud


----------



## bmwstephen (Jun 17, 2019)

Bills are not extreme because our weather is favorable. Since the region in California I live in has Mediterranean climate, there’s only maybe 3 months out of year where temps may creep slightly above 100 degrees F. But with 0 humidity, the house cools fast. In addition we have solar to offset.

It’s just conceptually I despise inefficiency.

Homes out here can only be built on slab foundations for costs and earthquakes.

Not to mention land here is pricey (i am sitting living in a 3000 sqft detached 2 story single family on a 4800 sq ft lot which is a joke elsewhere in the country but considered a mcmansion here). Builders now design homes to feel bigger than they are. As a result you hvac in an unvented attic is the current practice to maximize layout. Traditionally it would have its own hvac closet within the building envelope but the bean counter architects decided to replace that room for a powder room and relocate the equipment up above because the house would be more sellable.


----------



## Bud9051 (Nov 11, 2015)

Building it from scratch would have been an option, but converting back is unnecessary in your climate. Example, when a house is built super tight to make heating and cooling costs more reasonable they have to turn around and install air exchange systems to maintain enough air flow for indoor air quality. Many builders have a target where by they allow the house to leak to a level where they don't need the air exchanger. Not ideal but it meets their needs at a lower cost.

Where you are not paying a huge energy cost penalty I would not feel bad about what you have, it may have been part of their objective.

Bud


----------



## bmwstephen (Jun 17, 2019)

Hmm good point. But i guess are there ways I can make it any better while keeping the concept of ventilated?

I.e add roof exhaust fans or add batt between the roof studs (even though they have radiant barrier)


----------



## Bud9051 (Nov 11, 2015)

You wouldn't want to cover the radiant barrier unless you moved the vent channel to just below it along with r-60 insulation, yikes.

Two types of air sealing, house to attic and hvac ducts to unconditioned space, in this case the attic. Both of those can be tested by an energy audit. They can also do an infrared scan of the entire house while being either pressurized or depressurized to help locate leaks. When codes are tight (as in CA) those tests are part of the construction and results should have been passed along with the sale. I always advise a zip lock pouch and leaving all reports near the electrical panel.

A good energy auditor can generate the numbers you need to decide where best to invest in improvements.

Bud

PS, I'm not a fan of powered ventilation as lots of insulation can protect the house and attic temperatures have little effect on shingles, citations available.


----------



## AtticFoil.com (Aug 27, 2013)

This type of home can be tricky. Whole house fans really only work in moderate areas where it cools down at night. 

If bills are not too bad, then I would really make sure the ducts are super tight and sealed from sheetrock to sheetrock. Typically, the return air framing is not caulked to the framing around it etc. Also, make sure the boots are caulked/foamed to the sheetrock. If you change filter in attic, make sure the filter door is taped shut every time. 

Look at the attached picture. You can see the grey staining on the insulation where the air is being sucked in from the attic between the framing of the return air plenum and the sheetrock.

Ed


----------

