Energy Upgrade California—Up Close and Personal


Our furnace is approaching 25 years old and we have no cooling capabilities, so my wife Michele and I are looking into buying some new equipment before the temperature climbs this summer. I am especially interested in installing a mini-split heat pump, which would allow us to get rid of the ductwork and furnace in our unconditioned attic. But the initial expense may be a hindrance.

We knew that the Energy Upgrade California (EUC) incentives for retrofitting our home would not be around forever, so I contacted the EUC folks and picked an HVAC contractor, Stewart Heating and Air. I had met Bill Stewart, an icon of the HVAC and energy efficiency world of the Bay Area, at an EUC intro meeting at our local library three years ago. Bill’s company was getting customers $4,000 back for $8,000 of work through the rebates offered through the EUC program. Scott Mellburg of BayREN is our EUC advisor and is standing by to help us through the process and meet with us and our contractor any time we think it will be helpful.

Basically there are two ways to get the rebates. First, you can choose from a set of measures from a list that includes air sealing, adding insulation, and other retrofits. The measures you choose determine the amount of the rebate. Second, you can drop your energy use, according to modeling, by 10% for a $1,000 rebate, up to 45% for a $4,500 rebate (Advanced Home Uprgade). The cost of the audit, $300, will be reimbursed as long as work is completed through the Advanced Home Upgrade program. Michele and I are leaning towards the advanced option, even though we had air sealing done and insulation added to our attic several years ago, and it may be difficult to reach that 45% energy savings. 

This morning Rich Cunningham from Energuy (see photo), a third party auditor, came to do the energy audit. He performed the usual blower door and duct leakage measurements, took some electric plates off the outside walls to confirm that the walls have no insulation, did a number of safety checks including measuring CO levels, and looked at the crawlspace, among other things. Instead of depressurizing the house, Rich pressurized it to do the leakage testing.

Michele and I were working last night to clean out our fireplace, and I was pumping caulk into the space between the walls and the floor near the fireplace. Last time we had a blower door test done, the house was depressurized and we had some black soot spewing into our living room. No problem this time, with the pressure aimed out of the house and not into it. Rich explained that for some customers, feeling the air rushing into the depressurized home is a direct learning experience. The last time we had work done on the house, we could feel the air rushing in through the unsealed can lights all over the house. But we were sold on air sealing already and didn’t need the dramatic demonstration for a second time. In fact, our house may now be a little cleaner than it was last night after being pressurized.

Rich also pressurized the whole house, not just the ducts, to 25 Pa before doing the duct leakage testing. This is called “testing leaks to the outside”. In a week we will sit down with someone from Stewart Heating and Air to discuss the results of our audit, possible measures to install, and possible rebate amounts. Rich will come back after to do the test-out.

Here are the numbers so far (stay tuned for more):

Table 1. Air Leakage Tests (CMF @ 50PA)

Sept 2007 test in air leakage

Sept 2007 test-out air leakage

April 2014 test-in air leakage

April 2014 test-out air leakage

2,484

1,409

1,850

     ?


Table 2. Duct Leakage Tests (%)

Sept 2007 test-in duct leakage

Sept 2007 test-out duct leakage

April 2014 test-in duct leakage

April 2014 test-out duct leakage

33%

7%

22%

     ?

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Comment by George J. Nesbitt on April 26, 2014 at 8:49pm

I've been a fan (ha ha ha) of ventilation cooling since 1991. I was helping build a superinsulated house in the Sacramento CA suburbs, and living in a superinsulated retrofit (the contractors house). I would get woken up every morning when he turned the whole house fan on (a fan mounted in the ceiling, blowing air into the attic, and out the vents hopefully ;-) ). Fans integrated into the furnace make a lot more sense, and are hopefully more quiet, plus you don't have to open the windows, and it can be controlled by a thermostat.

Ventilation Cooling works great in climates that cool down at night. But sometimes it does not cool down at night, and that's when AC is needed.

Comment by Colin Genge on April 23, 2014 at 3:52pm

Pressurize the house to +25 Pa. Use smoke on the registers to identify leakage to outdoors then use a powered flow hood such as the Flow Finder to measure the loss rate.  If the ducts are inside the house, close the bedroom door, use smoke then powered flow hood. Most houses will lose about 20% even when ducts are completely inside the house with bedroom doors closed. This is super fast and effective way of determining duct losses. 

Then find some more bad stuff and make the sale. 

Comment by Jim Gunshinan on April 21, 2014 at 1:37pm

George, thanks again for you comments. I'll have to look the next time I am in the attic to see who made the damper system. I'm not sure the damper was every working properly while Michele and I have lived in the home. The return damper has never been connected to the juice to operate it. I'm curious how much it would cool the house at night if the damper system were up and working.

Comment by George J. Nesbitt on April 21, 2014 at 1:28pm

So, the cooling ventilation damper should be normally closed (motorized zone damper), and only open when cooling is called for (outdoor temp lower than indoor). Some systems allow for a partial open position for IAQ ventilation (only when the fan is on, hopefully cycled on/off with a control).

It is possible it's stuck in an open position. The damper should not blow open when pressurizing the house or the ducts (it would open when the house is depressurized if it was not a motorized zone damper).

What system do you have? SmartVent (Butler), Famco, or other?

Comment by Jim Gunshinan on April 19, 2014 at 4:16pm

I had a revelation while attending Bruce Manclark's session of duct leak testing at the Energy Out West Conference earlier this week: The damper for the duct that, if working right, will bring in outside air at night in the summer is not working and I thought, maybe it is stuck in the open position. That would explain the big unexplained increase in the duct leakage test user pressurized conditions.

But I just climbed up there and checked it. It is in the closed position. George, thanks for letting me know about the differences between the pressurized and depressurized house. Perhaps the pressure in the ducts pushed the damper open.

I also noticed that an access door to the blower fan was cracked open and the tape around it broken. I think I did that myself. Can't remember why I was looking at the blower fan. That could account for a lot of leakage from the air handler.

One thing we will do to decrease envelope leakage is invest in a chimney blocking device. That should bring our leakage down.

Comment by George J. Nesbitt on April 19, 2014 at 2:33pm

Blower Door; the 2007 test was a depressurization test, and the 2014 a pressurization test, which is almost always higher. The vast majority of "testers" are taught single point -50Pa depressurization. Pressurization requires a different reference hose set up with most equipment. Pressurization also requires closing off bath & kitchen fans, dryer vents, because the dampers are blown open. Some of the difference might be increased duct leakage, previous air sealing degradation, equipment calibration, wind conditions, equipment accuracy, or possibly work that created more holes.

Duct Test; The duct test results are more perplexing, and not likely explained by bumping the ducts changing the filter. The 2007 test would have been a +25Pa ducts wrt outside test. A friend played around with a standard test and a duct leakage to the outside test and got wildly different results. I'm not a fan of duct leakage to the outside, since most the ducts we are testing are all outside anyway (we have to do it to solve a "software" problem, but that's another story). The only other possibility is a duct has since become disconnected, or the previous duct sealing is failing (boots to sheetrock?).

Comment by Glen Gallo on April 15, 2014 at 8:59am

Nate,

RE: Duct test On my own home and a rental I have tested more than once over the last many years. I see no major difference. While it is not the exact number it is within a couple of percent. As far off as Jim's home is something does not make sense. The difference between 7 and 22 is not defensible.

I often see a difference in depressurization being the lower number. 400 cfm is allot.  I see greater differences with multiple tests with the blower door than I do with the duct tester. Wind can be a big factor. I think testing in both directions helps solve some of the problems.

The blower door I can accept easier than the duct test. But with both being off and not small margins and both weaker numbers it brings to mind many questions. It appears a failure somewhere occurred in either repair or testing. Maybe the failure is indicated with both tests being higher. With that test information I would look first to the ducting and sort it out.

The internet is great for discussions and learning purposes but I think boots on the ground would be necessary for real conclusions. I would be curious of the leakage to outside results.

Interesting post

Thank You Jim

Comment by Jim Gunshinan on April 14, 2014 at 11:01am

Thanks for all the comments. Yes, it is interesting how the duct leakage grew over the years. Maybe I bumped the ducts when I was changing my furnace filter...

Our energy bills, for gas (heat, water, cooking) and electric (plug load, laundry, lights) average about $40 outside of winter. During the winter, the heating energy use bumps it up to between $100 and $150. Not bad, but there is room to improve. It is just my wife and I and our dog in a 1,200 sf house in a climate where it gets down below freezing maybe one week total in the winter (Walnut Creek, CA). (When my brother visits from Phoenix, if we can talk him into coming over the Christmas holidays, we always have to bump up the heat!)

We are interested in a possible upgrade for three reasons: The rebates through Energy Upgrade CA are pretty generous (thanks PG&E) and won't be there for long. And we want to explore how to keep our house cooler in the summer. It gets over 100 F more and more of the summer, sometimes for a week in a row. Passive cooling measures and shade can't always keep up with the temperature. Third, our furnace and water heater are at or past there projected lifetimes and I would like to switch out when it is not an emergency.

I can't say we are motivated by our energy bills. It's more about comfort in the summer and adding value to the house. Now, if they only gave rebates for putting in a second bathroom!

Comment by Nate Adams on April 14, 2014 at 9:29am

As a few others have mentioned, it's interesting how much the test out from 2007 is different from the 2014 test in.

Blower Door: 400 cfm50 on the blower door could be within variance on a leaky house, but that's substantial on a pretty tight place like yours. Is that single component foam failing? Or different setups for the BD?

Duct Blaster: This difference is a bit shocking, could it mean that the mastic failed? Or tape? I haven't had the chance to retest a project, so I have no idea how my numbers would hold up. 

It brings up really interesting questions of variance in testing and measures failing more quickly than I thought. What is everyone else thinking?

Comment by John Proctor on April 14, 2014 at 8:39am

So Jim, any idea as to how your ducts sprung another 15% leakage between 2007 and 2014?

You also know that models are just models, not real houses and may not really represent what you have or will get from a retrofit. Our round robin HERS testing with modeled energy use provided estimates of cooling energy use differences of over 2 to 1 between the 6 HERS raters on three of the four Central Valley Research Houses (CVRH). http://www.proctoreng.com/utilities/wholehouse.html

We look forward to the follow up reports.

Thank you, John Proctor, P.E.

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