The purpose of this thread is to spark some discussion about Energy Star and the associated testing. I don’t have real in-depth knowledge, but still I thought it would be good for people who have not been through this process to see a little about how it works and probably some more experienced people like Jon or ShelterNeard could chime in and enlighten the rest of us some.
I’m gonna spread the photos over several posts…. first pics in the next post.
Later I will post some pics of the blower door test.
Edited 1/1/2009 9:56 am ET by Matt
Replies
Attached are some pics of the duct testing of one of several Energy Star certified homes I completed in 2008. Some years ago when I took my first ES building class the one figure that really got my attention was that the average duct installation had roughly 20% air leakage - WOW! That's potentially $20 in $100 that is being wasted... This all depends on how much of the duct system is contained within the conditioned space, and how much is in unheated/cooled areas.
The ES program I participate in seeks to limit duct leakage to less than 5%, and my houses typically test at around 2.5%. The test is done at 25 Pascals of negitive pressure. The percentage of leakage is expressed in CFMs as a function of the heated square footage of the house.
These first pics focus on prepping the duct system for testing. All supply and return opening must be plugged for the test. The tester used a coupla different methods for plugging holes.
If you right click on the pics and select "open in new window" it might work better for you, since the pics aren't really optimized.
pic 001: These foam blocks are used to plug the supply duct outlets. They are sized for the various common sized ducts.
pic 002: This one is for a 4"x12"
pic 005: Notice that the metal duct boot is sealed inside and to the sub-floor very well with duct mastic.
pic 004: Foam block inserted in the supply duct boot outlet.
pic 007: Sealing a return duct with plastic film and duct tape.
pic 019: inserting a foam block into a sealing supply duct.
pic 018: same as previous. Notice the cardboard insulation baffles at the attic/soffit intersection. Also notice the raised heel trusses.
pic 010: In this one notice the radiant barrier roof sheathing above the attic area.
pic 003: this shows how the first floor return duct is sealed while providing a place for the testing equipment to be installed.
Edited 1/1/2009 10:47 am ET by Matt
This next set of pics show the testing itself.
Again, the ES program I participate in seeks to limit duct leakage to less than 5%, and my houses typically test at around 2.5%. The test is done at 25 Pascals of vacuum (I think it is). The percentage of leakage is expressed in CFMs as opposed to the heated square footage of the house. So, on one house the heated/cooled square footage was 1350 and the 5% target was 67CFM max. It tested at 35 CFM of leakage at 25 Pascals of vacuum.
See the following pics...
Pic 008: The testing equipment is being set up.
Pic 011: another shot of the testing equipment connected to the first floor return.
Pic 013: This motor sped control is used to adjust the fan speed so as to "dial in" the correct negative pressure on the duct system.
Pic 015: The "Pressure Test and Flow Gauge" is showing 24.8 Pascals of negative pressure (is that the same as vacuum?) and it is showing 35 CFMs of duct leakage
Pic 023: This pic shows the clear tube that is inserted in the duct system via a supply duct to give feedback to the "Pressure Test and Flow Gauge".
"Some years ago when I took my first ES building class the one figure that really got my attention was that the average duct installation had roughly 20% air leakage - WOW! That's potentially $20 in $100 that is being wasted... This all depends on how much of the duct system is contained within the conditioned space, and how much is in unheated/cooled areas."
Good pics.
One thing about the duct leakage (and the benefit to having the ducts and equipment within the conditioned envelope) is, if you have 20% leakage, you are not only losing 20% of your conditioned air to the attic or crawlspace but your return is going to pull that same amount in from the exterior.
So you're not only losing it on the supply side, but you're pulling it in on the return side. If you're pulling warm moist air through the exterior you may have rot problems as well, if this happens long enough and the conditions are right.
I think sealing duct work is one of the lowest hanging fruits out there.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
the average duct installation had roughly 20% air leakage - WOW! That's potentially $20 in $100 that is being wasted... This all depends on how much of the duct system is contained within the conditioned space, and how much is in unheated/cooled areas.
Duct leakage in unconditioned space contributes not just to wasted energy (heating or cooling) but potentially to positive pressure (leaking return ducts) or negative pressure (leaking supply ducts) in the conditioned space.
Winter positive pressure will move more moisture-laden air into the thermal envelope, and summertime negative pressure will do the same.
The long-term moisture damage can be far more costly than the wasted energy.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
matt
Thanks for starting this thread. Would it make sense to seal ducts (picture 5) if you are only able to do it from the inside? I work on a lot of homes where it is almost impossible to get to the boots from the outside, but the inside of the unit would be practicle. What do you use as a sealer for the ductwork?
Many small steps can add up to increased energy savings, with not a lot of investment.
Thanks again
Greg in Connecticut
New construction or existing? I assume you mean existing. Also, do you mean flex to metal (boot) connection?) From the inside would help, but not as good as sealing the conections with duct mastic when the ducts are assembled in the first place. I believe hard ducts are often only sealed from the outside. In my expierence, if you have a duct system that isn't sealed well, taking it apart to try to re-seal it doesn't work very well. Duct mastic comes in one gallon plastic containers, is about the consistancy of thick pancake batter, and is applied with any old paint brush.
Matt,
This is a very interesting subject... I think that going throught the HERS rating process is very useful.
Learning the significance of tight ducts and airtight construction is priceless.
What was your score?
What is your climate zone and why are your ducts in an unconditioned attic?
How did you achieve your air barrier?
What about blower door results?
>> What was your score? << around 80. There were 4 houses of between 1344 and 1525 heated sq ft. My budget for ES was $2500 per house.
>> What is your climate zone << Central NC. Mixed heating and cooling.
>> why are your ducts in an unconditioned attic? << These are affordable homes. I install some energy upgrades in all houses. All upgrades home buyers have to pay for, but some are offered as additional cost optional upgrades. In the 4 or 5 years I've worked for this company, building in various neighborhoods, 2 home buyers bought energy upgrades. So, to answer your question, if someone wants to pay for that I'd be happy to do it.
If all the ducts are contained within the conditioned space the issue of duct leakage becomes negligible, by my way of thinking, so it is a really good thing. Still, in "normal" houses containing all ducts within the conditioned area potentially eats up living space or increases the area you are heating/cooling in the case of "hot attics" and conditioned crawl spaces. Obviously there are a hundred variations on configuration. A house with a conditioned basement with all 2nd floor ducts contained in the 2nd floor floor system would be a good example of all ducts in the conditioned space. These houses I built had an unconditioned CS with the air handler in the attic, which probably isn't the best for energy efficiency. I could have stepped it up a bit by adding maybe $4000 to the sales price of the house for a conditioned CS and 2nd floor floor trusses so that the 2nd floor duct system could be contained in the floor rather than the attic and the air handler would be in the CS. Unfortunately, I have to build houses that people will buy too. That $4k would have represented a 2 or 3% increase in sales price. Really though, there are other energy upgrades that are a much better value, like radiant barrier roof sheathing, which is projected to give about 1/2 return as all ducts in conditioned space but costs around $100. Looking at the upgrades sheet for one of these houses given to me by the ES rating company all ducts in conditioned space yields a projected monthly savings of $6.35 a month, so the payback time might be around 50 years - in this case. The example of the radiant barrier has a projected savings of $3.81 a month so the payback time of the $100 might be a little over 2 years - so, I installed that one.
If it were my house I'd probably install most energy upgrades short of PV and geothermal.
I notice that your screen name is HomeDesign, but you list you occupation in your profile as non-profit. I'd be interested in hearing about that.
>> How did you achieve your air barrier? << we will cover that later when we talk about the blower door.
>> What about blower door results? << we will do blower door once we finish with this duct part.
Just a note on running insulated ducts through the unconditioned attic.
This caused major ice dams in a new housing development in my area. There was enough "heat" coming off the insulated duct pipe to raise the attic temp above melting point but left the gutters frozen.
I think the ducts should have been under the attic insulation.
I am finding it very interesting whats been posted so far.
How many heating degree days is your climate? I bet the average temperature in Raleigh during January is around 40°.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
I'm in NJ and I don't know the answer. I going to check it out.
With the ice damning, it happened 3 times in a short while, all the effected homes faced north. The style of the roof did not help.
The heating unit is upstairs in a closet "blowing" into the ducts via the attic space. Lots of heat inside R6 insulated flex pipe. Just enough to melt the snow sitting on the roof. Made a real mess of the walls and insulation.
Act of God according to the builder! Took some real pushing to get it fixed!
Edited 1/1/2009 3:32 pm ET by USAnigel
Your situation sounds like a mess. I wonder how much of that was from insufficient insulation and how much was from leaky ducts. As Matt said in the first post, the DOE says that 20% of all conditioned air leaks out. If you have an air handler in your attic that is blowing 1,000 CFM at 100°, 20% leakage is 200CFM being exhausted in the attic.
I can see how snow melt would happen rather quickly.
Here's one place to find your heating & cooling degree days. Using Trenton NJ as your location, this report shows about 4,900 HDD with a base of 65°.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
With it being flex pipe I don't know how much heat comes from leaks. But when R38+ is required for the ceiling insulation, it throws me only needing R6 on the flex pipe. I think this was the required R value at the time. My house I would install R38 flex!
I'm thinking most of the "unwanted" heat radiates from the pipe. Yea its been fun fixing it all. Only 10 houses so far. Builder wanted to install heated cable as a full time fix. Just a little cheap!
Edited 1/1/2009 4:05 pm ET by USAnigel
If there was ice damming the obvious reason would be too much heat in the attic. Either because of air leakage from the living space and/or, as you say ducts in the attic. Re ducts in the attic the problem could be because of leakage, which I was hoping we could talk about here, or perhaps the R-6 is in-adequate. Here the current energy code requires R-8 duct insulation in unconditioned spaces, and as Jon said we have a lower heating degree day # than does NJ - obviously. Seems like NJ should be something like R-10. Here, I'd estimate that 98% of 2 story homes have ducts in the attic, so it's not like it can't work...
My guess would be that in the case you refer to is one of those cases of 20% duct leakage in the attic and a builder who didn't give a sheet about air sealing the top ceiling - probably installed can lights up there and the whole deal... Maybe some bath exhaust fans dumping air in there too. Wonder what those people's heating bills were like?
Trying to get this thread on track, I think the idea behind ES certified houses is not to say they are superinsulated or superefficient or anything like that, but rather the goal is to certify that they are not a POS like the ones you describe and are indeed reasonable efficient.
Trying to get this thread on track, I think the idea behind ES certified houses is not to say they are superinsulated or superefficient or anything like that, but rather the goal is to certify that they are not a POS like the ones you describe and are indeed reasonable efficient.
If you consider homes built to the current IRC Energy Code "reasonably efficient", then Energy Star homes are at least 15%-20% more efficient (HERS 85-80). And they're blower-door tested for air-tightness and certified for proper air exchange.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
No. To me the IRC/energy code is a bare minimum set of standards. To me the HERS 85 gets you only a reasonable efficent home.
And yes - I know about the blower door testing as indicated in earlier posts.
I remember reading about Energy Star or EEE houses from a few years ago. Lots of complaints about cost of complying with the standards.
Bit like autos and "we can be cost effective doing that".
I need to get round to building my own place! Do something crazy and do it right!
I remember reading about Energy Star or EEE houses from a few years ago. Lots of complaints about cost of complying with the standards.
Depends on who is administering the program. Here in VT, it's run by Efficiency Vermont, our non-profit state-wide electrical efficiency utility that's funded by a surcharge on electrical utilities.
They not only offer free plan review, free framing/thermal bridge inspection, and free final inspection and blower door testing, but then they give rebates for participating.
My last project earned $950 for the homeowner.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Seems the intention from the start has to be for an EEE building. My place is only 23 years old and you can tell the "standard" achieved is very low. I've had to make a few repairs and I find blackened insulation, holes poked in drain pipes, joints not glued. I find the same in many homes I work on to. Keeps me busy.
So like most "track" or "spec" homes built fast and by the poorest of workers.
At the far ends of the duct runs almost zero air comes from the vents. We need and should have much better standards built into the homes from the start.
Pressure testing, air flow, tightness, correct design. Payback for the home owner would be quick, but being as he's not paying for it as its built it's not happening.
Install a 90%+ HVAC and all we hear is "what's the payback period". Improved insulation gets the same question. We still don't get who is controlling the energy supply. Its cheap at the moment so don't bother!
Go back 3-6 months and the price of oil set a whole lot of things in motion. I still expect the price of filling the truck or car to be much more than rings up!
I would vote for real testing of new homes and I bet there is a job for getting "used" homes as good as they could be without going crazy!
I have to see what I can find in NJ.
Trying to get this thread on track,
Matt, It sounds like you are still predrywall?
Did your rater give you any good feedback at the walk thru?
Did he talk about thermal bypass? Thermal Bridging?
Did you discuss air barriers with him?
Was there an Architect or designer involved?
How good are your windows? Do you know your window to floor area ratio?
Do you have a good understanding of the reference house that your home is being compared to?
>> It sounds like you are still predrywall? << no - the houses are done. That is how I got the final HERS ratings I gave you above (and the ES certificates).
>> Did your rater give you any good feedback at the walk thru? << Yes - they picked up a coupla penetrations I had missed. Also, on one house she told me that one of the bath fans wasn't functioning. Turned out that the exterior flapper was painted shut.
>> Did he talk about thermal bypass? Thermal Bridging? << yes - I know about that stuff. They give you a bypass check list to go through. Regarding bridging, this is just standard frame construction - so yes, there is bridging.
>> Did you discuss air barriers with him? << Maybe I shoulda stated in post .1 that I've built 18 ES certified homes to date. Ten years ago we even build side by side homes of the same size and very similar layout. One ES, one not, and compared test results and performance.
>> Was there an Architect or designer involved? << We rarely use Architects here in single family residential, but yes the houses were designed by a designer.
>> How good are your windows? Do you know your window to floor area ratio? << The windows are Low-E U 3.5, which is fairly minimal - like I said - affordable homes. The fenestration calculations are required to be on the plans for plans review/permitting.
Do you know anything about duct sealing and the associated ES testing?
Do you know anything about duct sealing and the associated ES testing?
Matt, I think I see what you are doing ..you want to talk about duct sealing first and then move on to air sealing..I just had the wrong idea.
First concerning duct sealing .....Do not use Duct tape to seal ducts!
Use mastic at all connections. Inside the joint and outside if possible.
I use metal duct and try to keep the duct runs short and simple.
Ducts and air handler inside the conditioned envelope.
The ES testing was easier in my case beacause my mech contractor sealed all of the duct openings with cardboard and tape in order to keep construction dust out of the ductwork during construction.
The Rater did the same duct blaster test(same pressure) that you illustrated.
My 1800 sf house tested at 16 cfm leakage... I do not have a percentage number for you .
First concerning duct sealing .....Do not use Duct tape to seal ducts!
There is only one good use for duct tape and poly:
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
So what's the shelter in place pic???? One of those "in case of nuclear disaster" type of deals.... 6 or 7 years ago DW made me go out and get some plastic and duct tape....
See attached pic... this is my idea of the proper way to deal with a disaster.... ;-)
matt..... that was a .dochow about a .jpg ?Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
I got some time to respond now. Went to work today to fix a framing F-U. Yea, I got guys to do that, but they built as I said, and the the plumber said "how is the W/H gonna fit through this door way?" Sheeeeet!!!! I take responsibility for my mistakes - just like I expect other people to...
Anyway, sounds like you have < 1% leakage on your ducts. That's awesome!! When I first got involved with ES 9 or 10 years ago I think they had a 1.5% leakage requirement - can't remember the exact #, something like that, anyway, the HVAC co we had at that time were looser - I wanted to fire them, but I don't always get to call all the shots.... They simply couldn't make the spec. Moved on since then.... Got a better HVAC co.
Anyway, 1%- wow!!! - you say that's your own home... Not too long ago I had a RE agent say "any house you build should be just as good as you would build your own...." Yes - agreed, as long as they want to pay for it. On my own home, 10 years ago, I worked 16-18 hr days for a year in order to get what I wanted.... I'd charge a pretty penny for that....
Had any homes tested that you built for other people?
Anyway...
What do you figure was the up charge for the metal ducts? Or maybe flex duct isn't popular where you live? I haven't seen metal ducts here in at least 20 years - except for plenums and distro boxes. I have never taken any flow dynamics classes like you archis probably have, but I can see that obviously flex doesn't flow as well.... I think they just up-size one size to compensate? Anyway, the metal ducts having to be insulated after the fact has gotta be expensive... And I don't really see how the hand installed insulation could be as good as the factory insulation on flex.. ? And I guess it's done with duct tape??? Here, conditioned space requires R-6 duct insulation and R-8 in unconditioned... I'll put the "ducts in conditioned space" on the list for my next personal house... If the boss lady lets me build another...
Anyway... today, I sent an E-mail to one of the ES field test techs who I'm friendly with and asked if the leakage requirement for ducts in conditioned space is any more lax... logic would say that it is not as important... We will see what she says...
BTW- My mechanical contractor nails siding "boards" over the floor supply boots until trim out. The ES tester temporarily removed the boards for the testing.... So yes, they are covered to prevent dust and debris from entering the duct system. It's also a safety thing... On the ceiling ducts, can't say I see the point.
On your house what is the general config? Basement? Conditioned crawl? Two story? Second floor floor system trusses? What??? I know they build a lot of slab houses in Texas.... I build them too but I hate 'em...
Matt, I will get around to all of your questions.
I can not take credit for the tight ducts and the ducts do not really need to be so tight when they are within the conditioned envelope.
Credit for the tight ducts goes to my mechanical contractor.
I will take credit for finding the right contractor.
As to the cost of my personal home.. I am a cheap and frugal.
I did not spend a fortune. I achieved a HERS 51 for about $100/sf.
I was the GC and Architect and Gopher ...so that cost was not included.
I like this quote "you get what you inspect..not what you expect"
I like this quote "you get what you inspect..not what you expect"
Right... but you can still only expect so much for x number of dollars...
Here is some pics on blower door testing. Didn't take a lot of pics on this subject.
The ES requirement is that the house have < 10% leakage when tested at -50 Pascals of pressure. The 10% number is 10% of the house volume and is measured in CFM. This particular house was 1525 heated sq ft (upstairs larger than down), 9' ceilings down, 8' up, and has a total volume of ~12,955 cu ft. So, the target of 10% for envelope leakage is < 1295 CFM.
Pic 002: The blower door setup.
Pic 003: The readings of 947 CFM at -48.2 Pascals of pressure on the Pressure and Flow gauge. Not sure why he didn't adjust the fan speed for a bit closer to 50 Pascals neg pressure, I would assume that the adjustment is rather touchy...
Edited 1/3/2009 9:19 am ET by Matt
Matt,
those are good numbers!
Just from the blower test alone...It looks like you are building homes that will use much less energy than homes built to the current energy codes.
And your homes are affordable.
How did you achieve the air tightness?
Edited 1/3/2009 9:45 am by homedesign
>> How did you achieve the air tightness? <<
First, as far as I know, they don't give you extra HERS points for lower blower door test scores... At least I don't think so. Anyone know anything about that?
And now to get to some of your earlier Qs. The air barrier is essentially just the drywall. All penetrations in the drywall on the perimeter of the conditioned air space envelope - HVAC, plumbing and electrical or caulked, foamed, or whatever to achieve the air barrier. I didn't really take pics of too much of this stuff as I didn't know we were gonna be discussing it. I did just now hunt around my pic folders for some related pics though....
First as SOP, before insulation electrical, plumbing, etc penetrations See "foam sealing" pics attached. The red foam is fire retardant.
Doors and windows are foamed, too - by my insulator. They have a up-charge for this.
Also, the exterior wall plates are caulked to the subfloor. As far as I know this is a major leakage point. This can be seen in pic "air barrier". Also notice the cardboard air barrier behind the under stairs kneewall, and note that it is foamed or caulked around the edges. This is part of the ES requirements and is done behind any fiberglass tubs on exterior walls, duct chases or pre-fab fireplaces. Any other obvious air leaks in the framing are caulked too and I use Insulated headers, "energy corners" and Energy Ts in the framing although these aren't directly for the air sealing thing, but more to reduce thermal bridging and air pockets in the frame assembly. I don't think they give you HERS points for these details either..
Another thing I do for air sealing is after drywall but before HVAC and electrical trim outs I go up in the attic and look for light coming up through the ceiling drywall and boxes. The bath exhaust fan boxes and electrical boxes are build like swiss cheese. I use caulk, duct mastic, or whatever to make it so no light comes up through - I didn't photograph this... Attached are some pics "ceiling leaks" from some time ago in an attic showing normal leaky ceiling boxes and also the pics "Leaky electrical boxes". Regarding the can light pic - I don't install those with an attic above - of, if I did they would have to be covered with some kind of box to give both clearance and air sealing - or I guess I could find some E$$$ rated ones... Also attached are some pics I tool in Minnesota of electrical boxes ("MN electrical boxes") that are designed not to leak air. Pretty cool, but I have not seen them around here.
DW is "summoning me" so I gotta go...
Edited 1/3/2009 12:09 pm ET by Matt
Another thing I do for air sealing is after drywall but before HVAC and electrical trim outs I go up in the attic and look for light coming up through the ceiling drywall and boxes. The bath exhaust fan boxes and electrical boxes are build like swiss cheese. I use caulk, duct mastic, or whatever to make it so no light comes up through - I didn't photograph this... Attached are some pics "ceiling leaks" from some time ago in an attic showing normal leaky ceiling boxes and also the pics "Leaky electrical boxes". Regarding the can light pic - I don't install those with an attic above - of, if I did they would have to be covered with some kind of box to give both clearance and air sealing - or I guess I could find some E$$$ rated ones... Also attached are some pics I tool in Minnesota of electrical boxes ("MN electrical boxes") that are designed not to leak air. Pretty cool, but I have not seen them around here.
Matt,
I just remembered your comment about going in the attic and looking for light coming thru. Such a simple thing could really improve the general housing stock!
Especially the ones that are not being rated. I believe that air sealing is more important than r-value.
Have you tried it at night with bright lights from below? How about from the crawl space?
I realize it does not reveal all of the leaks..but it will sure get you thinking where other leaks might be.
Edited 1/9/2009 11:06 am by homedesign
Also, the exterior wall plates are caulked to the subfloor... Any other obvious air leaks in the framing are caulked too
Caulk might get you past the blower door test, but the problem with caulk is its longevity and ability to resist movement and shrinkage.
To properly employ the Air-Tight Drywall Approach (ADA), all framing assemblies need to be sealed to each other with either EPDM gaskets or non-hardening acoustic sealant (Tremco), which is also used on the polypan electrical box shrouds.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Matt,
I know it is not your fault(the builder) that the mechanical and the ducts are not inside the conditioned envelope.
It is HomeDesigner's fault (myself included..get it) for not providing the space.
BTW the Irish humor was good
Matt,
I have designed many Energy Star Homes without any special attention.
I let the builders take care of the details... lots of 80 to 85's..passing was the only goal.
One SIP house that scored a 50 HERS(helped by geothermal)... a stick frame that hit 65 HERS and my home at 51 HERS (no geothermal)
My plan is to keep improving and I have some new ideas on how to do it.
I don't know the upgrade cost for flex duct to rigid...I will ask my mech contractor.
Most homes in North Texas use flex duct.
Wrapping the ducts was not a big deal...did not take them long.
I believe you will improve your HERS score by using your actual blower door test instead of the default value for air changes....assuming that you test out better than the reference home.
Concerning Thermal bridging....You can also improve your score if your actual wall framing fraction is less than 23%.
You do not even have to do advanced framing to improve the score ...studs at 16 oc will work.....just get rid of the unnescessary wood....I noticed that you had 12 studs supporting 4 trusses.
If you would right size the headers and studs then you will likely beat the default.
Your Rater may not want to bother to calculate your actual framing percentage...but if she did then your score would likely improve.
Most raters like to leave the software on the defaults...all they care about is pass/ fail.
If you really look hard at the rating details ..you may start to approach the tax credit thresholds.
For a few more bucks then(I think you can still) get the $2,000 tax credit...that is way better than a deduction.
It sounds cheesey trying to "Game" the rating system...but most of the points actually do translate to energy savings.
As to covering up all the registers..it is part of our local GreenBuiltNorthTexas protocol....
The idea is to keep sawdust and drywall dust..mud dust out of the ductwork.
I will hit some details of my house next time.
Matt do you understand the parameters for the reference home?
You are right - these houses received no special attention from the designer to address energy efficiency. It was all left up to me.
>> I believe you will improve your HERS score by using your actual blower door test instead of the default value for air changes....assuming that you test out better than the reference home. << Not sure what you mean. I had the blower door test done. Maybe they did factor that into my score?? Maybe I'd better ask the Rater??? They gave me a complete report on each home before it was built.... Maybe I'm supposed to get one after it is built and tested?
>> You do not even have to do advanced framing to improve the score ...studs at 16 oc will work.....just get rid of the unnescessary wood....I noticed that you had 12 studs supporting 4 trusses. << what pic was that in? I'm all about getting rid of extra wood.
>> If you would right size the headers and studs then you will likely beat the default. << Right sizing headers has been somewhat problematic for me in the past: Framers get confused: Often times, if going to a smaller header creates a 2" or 3" gap (above or below the header, they will fill it up with 2x4s or whatever. 2) Here, designers and engineers like to add this note to plans saying "all exterior headers are 2x10s UNO." I've asked them not to do that... Usually they still do, and occasionally I really don't get any input into the plans - it's more like: "Here, build this". . Once an inspector made me get a stamped engineer letter because I did 2x6 headers on openings < 3' just because the note was on the plans - another $150 wasted... (for the letter). OTOH, next house I'll try and see if I can beat the 23% figure you mentioned.
>> Matt do you understand the parameters for the reference home?<< No I guess I don't. I just looked through all the info they gave me and I didn't see much of anything... I assume the the reference house is a theoretical house that is of the same size and configuration as the house to be built, only the reference house is just a code basic house with average construction details???
Matt, you may have to request the rater to rework your score after the duct blaster and blower door tests...They are more geared to just making sure that you hit the 85 threshold.....But you are going to extra trouble and you should get some bragging rights.
The picture with the surplus studs was number 19.
I see that happen a lot ...the framer may not have the exact size for the windows so she oversizes the opening and then fills it in with extra studs when the windows show up.
I think you understand the reference home concept..It is a geometric twin of the rated house with energy code minimum components. I have a doc with more details.
more later..thanks for the dialogue
Edited 1/3/2009 8:14 pm by homedesign
>> The picture with the surplus studs was number 19. <<
Oh yea.... that was a mistake on the framer's part on that particular house. Window size was on the plans but they got mixed up somehow.
Matt, I saw your exterior photos in your Photo Gallery Thread
63152.68
...Very Nice
Your homes are even more Energy Efficient than your HERS Score reflects.
Big problem with the HERS index is that you are comparing your house to your geometric twin.
The homes that you are building will use MUCH less Energy than an Average new home of similar floor area.
Most new homes because they are cut-up with lots of corners will have more exterior surface area than your homes.
Matt,
My house is a slab on pier foundation.
Here is a link to some photos ..should answer most questions.
112064.1
John B
Wow - you did a lot for $100 a sq ft!!! Is that right? Still, hard to compare building costs between different geographies though not knowing the cost of living etc. Did you do some of the on-site work yourself? I notice that the pics span > 2 years...
I watched each slide show 2x, and then went through each pic individually so as to look more closely and read the accompanying info.
I'd still like to know exactly what you did to get from the standard 85 HERS to 51. That's a 34 point jump!!! Looking at the sheet from one of my houses:
Ducts in envelope: 5 pointsSpray foam insulation: 8 points
That's only 13 points I got you so far...
That blower test is awesome - did they give you points for that? Did it test even better after DW?
BTW - thanks for discussing this stuff with me. I want to learn some stuff that maybe I can apply to the regular houses I build.
PS - I'm be posting some comments about your house itself in that other thread later. I love it...
Matt,
It took 4 months to build the house...maybe the time stamp was off on one of our cameras.
The only Sweat equity was the trash management...sweeping..sorting..recycling
I'd still like to know exactly what you did to get from the standard 85 HERS to 51.
Matt, It was a combination of a lot of things.
The climate is hot/mixed humid...
Conditioned attic ..all mechanical in the conditioned envelope.
The daylighting in our house is very good yet the window area to floor area ratio is very low compared to the reference house. The windows have low SHGC numbers ..good for this climate and low u-value.
Energy Star does give credit for proper window orientation and exterior shading. Our house has most glass located on the North and South..Majority of the south glazing is shaded in summer.
East facing glass is limited and west glass is extremely limited.
We got an extremely good rating for the quality of the insulation install.
The Air tightness was factored in.
High efficeincy Sealed combustion Furnace with ECM motor.
16 seer ac with 2 stage compressor.
A light colored roof and light colored walls in my climate reduced projected energy use and reduced the HERS rating.
Energy Star diswasher and ceiling fans.
Very high percentage of pin-based fluorescent lighting.
The efficient lighting also reduced the cooling load (and increased the heating load)net reduction in energy use.
Setback thermostat with humidity sensing.
Energy Star exhaust fans.
Honeywell make-up air controller.
Wall insulation was upgraded in some areas to double studs with 7" open cell foam.
I will think of more later.
Coupla quick Qs if you don't mind:
>> Setback thermostat with humidity sensing. << What does the humidity sensing do? Continues to run the AC until both the temp setting and the humidity setting are satisfied?
>> Honeywell make-up air controller. << What is that? One of those air cyclers that runs the air handler blower periodically?
Matt,
The stat is linked to a variable speed blower motor and will adjust the speed and call the ac depending on humidity. Only works during the cooling season.
I also have a stand alone dehumidifier for shoulder seasons.
The honeywell controller is an air cycler.
It is programmed to meet ASHRAE standards for ventilation.
Humidity during winter is reduced by increasing ventilation run time.
Edited 1/4/2009 9:51 pm by homedesign
Thanks...
The first ES houses I built had the air cyclers. ES people stopped asking for them and the HOs just didn't understand them. So, you don't have and ERV or similar? Just the fresh air induction into one of the returns?
Is the HVAC sys zoned - ie - are there 2 thermostats?
Matt,
I have a way to add an hrv in the future.. I have just recently realized that HRV is worth it.
Conventional wisdom around here was that the HRV was not worth the expense.
After looking at what the Germans are doing..I have changed my mind.
I am going to upgrade the wall insulation and add an HRV in my next house.
the fresh air damper goes to the single airhandler.
It is a 2 zone with 2 stats
How do you get regulated makeup air in your tight homes?
Edited 1/4/2009 10:25 pm by homedesign
home.... do you have a brand / model of the hrv you're looking at ?Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Mike...have not done much research yet.
But I will....maybe a few months before I add it to my house.
some of the sites are single mfr.
looks like i'm looking for an ervMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
some of the sites are single mfr.
not sure what you meant
looks like i'm looking for an erv
Are you sure ?... I thought HRV is better for Cold climate.
Are you looking to dehumidify?...If so just bring in more outside air with your HRV?
our long heating season is November - March
super insulation reduces that to say...Dec, Jan, Febthen it's no, heat.... leave the doors and windows closedthen we get into the A/C season....4 - 8 weeks( July - August) with extremely high coastal humidityApril, May, June & Sept, October are the tweenersin the heating season we have to watch our interior RH in danger of getting too low
my understanding is that the ERV helps to keep the interior air humidity levels either higher ( in the heating season ).... or lower ( in the A/C season )my initial reading is that ther is more benefit to me with an ERV than an HRV.... buti haven't given my credit card nmber to any of the mfr's yet...
still in the " pick everyone's brain on BT " modedo you do any of your own energy testing.. like blower door...?Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Mike,
My understanding ..if your house is tight and well insulated then you will produce more internal moisture than you need...if your house is too dry then you are leaking or overventilating.
Robert seems to have a better explanation.....posted somewhere.
well...i'd grant that...in normal circumstances
but it doesn't answer the dehumidification loads for summer
at this preliminary stage in the decision, i like the greater control they are touting for the ervMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
but it doesn't answer the dehumidification loads for summer
Mike, If you carefully size your ac so that it is exactly or perhaps smaller than the load.... then it may run long enough to dehumidify.
Joe Lstiburek told me that many high performance homes that are 2,000 sf or less may need an additional dehumidifier at times.....part of The price you pay.
His answer was to "just pay it and get over it" (until they improve the equipment) <Not sure if it applies in your climate>
I have a stand alone dehumidifier and use it occasionally.
John
Edited 1/5/2009 11:29 am by homedesign
home.... for a/c i've been buying two or three window units ( about $120 each )
and installing them in special thru-wall sleeves in strategic locations.... so our A/C equip / labor costs are well below $1000 for a single floor , 3-br house
so i'm not enamored of "just pay it and get over with"
super insulation moves into new territory Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
how humid is it inside your home in the summer?
do you have a humidity problem when you run the ac's?
do they short cycle?
hmmmm... I sort of remember that thru wall ac not so good.
Have to check Joe's top ten list
at this preliminary stage in the decision, i like the greater control they are touting for the erv
what kind of control?
Mike, have you had a blower test done?
I am guesiing your houses are tight.
i have.... a friend tests all of his own insulation jobs.... it's very tempting to get me own BD test kitMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
but it doesn't answer the dehumidification loads for summer
If your AC is not adequately dessicating the air, then using an ERV may help dry the incoming air somewhat, but proper installation is key. Make sure you check the TRE (moisture transfer) rating at design air-flow. I understand that some dessicant-wheel ERVs can quickly become saturated and lose efficiency.
Check out these reports:
http://www.advancedenergy.org/buildings/knowledge_library/ventilation/erv.pdf
http://www.totalairsupply.com/5%20May%2007%20Tech%20to%20Tech%20Column--HRV-%20ERVs.pdf
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
i read that about the desicant wheel systems toobut... it seems like they are talking about below the mason-dixon line
here... i'm talking about bringing in fresh air and dehumidifying as an assist to the window shakershere's from one of your links...
<<<<As Davis explains, in a southern climate, most of the ERVs
job during the summer months is removing moisture from
the incoming air. “In Raleigh during the cooling season,
your major load is going to be the moisture in the incoming
air stream,â€says Davis. “To achieve space-neutral condi-
tions during the cooling season (75ºF (24°C) and 50% rela-
In Davis’ own home, the
costs of using his ERV amounted to less than $10 month,
providing a safe level of 0.65 air changes per hour all year
round. That equated to 167 kWh of electricity per month
to run the ERV motor, and to operate the heat pump to
condition the fresh air drawn in by the ERV. For a safe,
comfortable home, $10 per month is a small price to pay.
>>>>>Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
another good site... but as always... conflicted<<<<The argument for/against installing ERV’s in Colder Climates:
There are people on both sides of this issue and from all I have read it is a matter of
preference. Everyone I talk to here in the northeast swears you should use an HRV.
They claim the performance difference is not great enough to justify using an ERV in
colder climates and it is better to have a humidifier to add humidity. They also say the
potential damage to the paper based permeable filter material from frozen moisture can
lead to air leakage, loss of efficiency and airflow.
While researching this article I found many saying just the opposite. They said the fact
that the ERV doesn’t remove as much humidity in cold whether from the home, doesn’t
produce condensation (but has moisture and can freeze), would require defrost only in the
coldest days, doesn’t have significant airflow restrictions unless the outdoor temperature
is below zero and will deliver drier air above 40 degrees Fahrenheit make it a great
choice for this region.
ERV supporters also claim that the HRV will spend a considerable amount of time in the
defrost mode in our region, effecting the airflow and ventilation of an HRV.
The one thing that stands out to me is whichever you use in this region; it might be a
good idea for it to have the capability of defrosting itself.
Efficiency:>>>>my next project will be a hybrid.... add on to an existing 26 x32 gambrel and basically double the size..
the existing was well insulated for it's day... 2x6 (fg ) , 2 foam under the slab
the new will be 2x6 mooney with dens-paki'm pretty sure the total structure is going to wind up easier to heat and cool that the existing ...... but there will be many challenges tying the two systems togetherso far ... my heating is going to RFH in the new, keep the old with its passive solar gains and electric resitance heatadd some form of A/C... and ERVanother challenge will bethat they want 3 fireplaces....Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
do you do any of your own energy testing.. like blower door...?
No.. I used local energy auditors.....For ENERGY STAR
Some of the cities near Dallas require ENERGY STAR Rating
The blower door test is very useful ..maybe if you are not looking for energy star brownie points then you will not need a full audit.
Maybe just pay the gal (Dorothy)for the blower door test.
If you build several homes then owning a blower would be nice.
Eventually you would get an idea where you leak.
"my initial reading is that ther is more benefit to me with an ERV than an HRV.... but
i haven't given my credit card nmber to any of the mfr's yet...
still in the " pick everyone's brain on BT " mode"I would pick their brains on this topic at this site too.http://hvac-talk.com/vbb/
in the heating season we have to watch our interior RH in danger of getting too low
Then you've got a leaky house. That's the only way that humidity drops in the winter is by heating large quanties of outside air to lower RH.
Any tightly-built house should have too high a RH in the winter (typical family of 4 puts 3 gallons per day into the air).
Edit: homedesign already said this.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Edited 1/5/2009 2:33 pm ET by Riversong
yeah.... absolutely..... 1985 and double wall was nowhere near what we can do nowMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
>> How do you get regulated makeup air in your tight homes? <<
it's just a filtered 6" duct that lets fresh air directly into a return. There is no dynamic regulation. Only a manually adjustable damper.
Regarding the HRV, I asked the ES people about that and they said they felt there were better upgrades to spend money on. It isn't on their list of recommended upgrades either. In your case, it doesn't sound like you held back on much of anything, energy wise, short of PV or geothermal so a recovery ventilator would be a logical next step - I guess. I woulda thought you would be looking at ERVs though... Don't know much about it though. When you said "what the Germans are doing" do you mean German made units or the way they are utilizing them in their HVAC systems?
When you said "what the Germans are doing" do you mean German made units or the way they are utilizing them in their HVAC systems?
I was refering to the German passive house strategy.
There is currently a discussion in the Green folder. 114460.1
I agree about an HRV not being much value until you have done the other stuff.
I am still undecided about ERV vs HRV for my climate..Hot Mixed Humid.
I would need to look at the Energy cost /benefit over all 4 seasons.
Edited 1/5/2009 6:39 am by homedesign
All: I scanned in the attached document today at the office. It shows projected savings for a basic Eenrgy Star HERS 85 house of approximately 1400 heated sq ft. (base energy costs of $116 monthly for the HERS 85 house vs $127 for a regular code built house). Not a huge savings. Like I said, mine came in at around HERS 80 with a ~$2500 expenditure on base ES requirements and upgrades (which included the cost of testing and certification which was around $600 (I got some kind of affordable housing discount - and I think the normal price would be around $1000)). So that might equate to $110 a month average base energy usage. So, monthly savings for my hers 80 house might be around $17 a month - average - as compared to a "regular house". So, $2500/$17=147 months, or 12 years for payback...
Looking down the attached sheet at the recommended upgrades, unless you have lots of $$ and can do 'em all, the idea would be to pick upgrades that give you the most bang for your buck. ie - least payback time...
For example, off the sheet, for this house:
Most bang for buck:Electric W/H upgrade EF=80 to EF=90. Cost zero. Savings $3.81 a month, or instant payback (turns out that most modern electric W/H are EF=90 so it is a free-be.) this is on the 2nd page of the sheet. Also, I think this was required for the base HERS 85 rating. Instant hot water only works out if you have natural gas.
good bang for buck:Radiant roof sheathing: cost: ~$100. Savings ~$3.81 a month. or a 26 mo payback.
Medium bang for buck: upgrade 13 seer AC to 14 seer: cost $475. Savings ~$3.81 or a 124 month payback.
Low bang for buck:All ducts in (conditioned) envelope: estimated cost ~$4000!! Savings ~6.35 a month or a 629 mo payback!!!!!! or ~50 years!!!!!
BTW - this is how I derived the $4000 number: Sealed CS $850. (already bid) Upgrade 2x10 2nd floor floor system to 14" tall open web floor trusses so I can fit the ducts in there: (ESWAG) $500 (Ive bought lots of em). Here is the kicker though. These houses were very tight designs (spacewise) so with all 4, the house would need to be 1' deeper adding 48 sq ft to the house (24' up and down) in order to accommodate the 14" floor system and an extra step. Figuring that larger house at a modest $55 a sq ft (for empty space) = $2600.
So, overall, my 2 main points are: 1) this stuff ain't cheap and the payback for most energy upgrades isn't real quick.2) Again, unless you have lots of money pick your upgrades wisely trying to zero in on the most bang for buck. Or, you can just throw darts at the dartboard while blindfolded.
Your mileage may vary depending on climate, etc, etc, etc, etc.
As a matter of interest some of the upgrades I did put on these 4 houses were:50% pined based florescent lighting (required for the basic HERS 85 rating)(not CFL)14 Seer AC unit on one house (got a rebate for the elect co)radiant barrier roof sheathing (2 houses)upgraded wall insulation (all 4 houses)upgraded ceiling insulation (2 houses)EF 91 electric water heaters (there was no gas)ES package from HVAC co which included extra duct sealing, filtered fresh air induction duct, etc (required for base ES 85 rating) (I think the cost was aorund $700)
Side note: I also had installed a zoned HVAC sys in each house - which wasn't required nor really an energy thing, but would help insure HO comfort and no callbacks for that. This cost ~$1000 per...
Matt, lots of good info and thought there.
There is a volume builder in Oklahoma that builds Energy star Houses and they decided to keep thier ducts in the attic also to keep things affordable.
I know.. you have to keep it affordable. At least your ducts are tight.
I also get your point about these things adding surface area and square footage.
A local builder here lowers the ceilings in his hallways to accomodate ducts.
He still has to give up some floor space for his furnace closet.
All about trade offs. Another problem with extra thick walls is the extra square footage... A lot of our costs are tied to sf.
And don't forget property taxes..the gift that keeps on giving. We have to pay property tax for those extra sf.
AS far as your sf costs..I have not seen anyone around here build affordable homes even without energy upgrades for near as low as you.
Around here we factor in the price of the garage so it drives the cost per ac foot up some.
Anybody else have an Energy Star story?
Let me clearify a few things about the SQ FT number. 1) I did not include the lot cost, as I assumed you did not either. I'm guessing your infill lot was fairly expensive, whereas our lots were fairly cheap - as building lots go. 2) Also the # I gave was cost to build - not cost to home buyer. In these market conditions we have lost money on some houses we have sold within the last year, however on these ES homes we actually made a respectable profit, based on the fact that that location is in demand and the supply of downtown building lots is very short. Again, I assumed you gave build cost - not sales cost - since you were not selling it. OTOH, these homebuyers moved in with probablly 20% of instant equity based on the price caps imposed by the city.
Matt, you are correct...my cost was for everything except the lot.
And I was not talking about sales price.
I did have some expensive earthwork ..brought lots of expensive select fill to get good drainage and had to include some deep concrete piers..this was included in the sf cost.
Around here builders usually mark up about 15 to 20% of costs to cover overhead and profit.
"14 Seer AC unit on one house (got a rebate for the elect co)"I wonder how close they monitor that.A 14 Seer AC unit, INSTALLED might not be a seer 14 system.I can't remember the name off hand, but there is an association HVAC industry that people than has the offical list of equipment and ratings.The installed SEER depends on the coil set that it is matched to and t he air handler.A given 14 seer, 3 ton compressor when installed might range from 13 to 14.5 seer.I am kind of guess at those number. But I remember seeing a wide range when look at the tables..
William the Geezer, the sequel to Billy the Kid - Shoe
I don't really know much about that except one of the ES requirements is that the indoor and outdoor units have to be matched - ie properly sized for each other. These were all Trane heatpump houses. Also, the ES program requires that the equipment be selected based on a manual-J load calc and the load calc has to be submitted the ES rating company.
Bill and Matt,
In my case the outside unit is rated up to seer 17 ..but the rating that was reported to the energy auditor was the matched set rating of SEER 16.
"I can't remember the name off hand, but there is an association HVAC industry that people than has the offical list of equipment and ratings."
I think you're talking about ARI. They have a number that corresponds with each system out there, at least as far as I know. So you can look up your exact heat pump (size, refrigerant type, efficiency, etc.) and match it with the exact air handler you're using and know if you will get the efficiency you're paying for.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
That is the one..
William the Geezer, the sequel to Billy the Kid - Shoe
Homes:
I looked up some figures at the office today. These houses costed out at around $68 a heated sq ft. I subtracted out design and engineering fees, since, comparing to your $100, I imagine you got that for "free".
it's just a filtered 6" duct that lets fresh air directly into a return. There is no dynamic regulation. Only a manually adjustable damper.
The problem I see is how do you get fresh air in the shoulder season unless the homeowner is instructed to run the fan?
>> The problem I see is how do you get fresh air in the shoulder season unless the homeowner is instructed to run the fan? <<
Exactly. And if memory serves, the air cycler is fairly cheap.
OTOH, at my own house - not an issue. DW has this thing about having windows and doors open except in the very hottest and very coldest weather. Granted, that is not as good as the forced ventilation to all rooms of an air cycler/HRV/ERV but I think it is adequate.
I notice that your screen name is HomeDesign, but you list you occupation in your profile as non-profit. I'd be interested in hearing about that.
Matt, I do make a profit...Architect was not a choice.
I updated my age and occupation...I don't know how it was switched to non-profit.
Yea - my profile got changed a coupla times - actually blanked out...
Here you go.
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
thanks..... here's a Guiness for yaMike Hussein Smith Rhode Island : Design / Build / Repair / Restore