Energy effeciency of new home

[gonefishin]

WE are building a 3500 sq foot home in Ohio. Front door faces east Back door faces West and sits on a hill.

I have been talking to reps from Low-E to find ways to lower our utility bills when this project is complete.

We are going with a 6ton WF geothermal.

I wanted to know what you thought of these fairly new products:

1.) Slabshield- polyethylene foam with aluminum: placed under the basement before cement is poured. This provides an R value of R3
Simple to install and replaces the mil vapor barrier. Cost is mid 40cents per foot.

2) Low E- House wrap. Aluminum coated W/ closed cell polyethylene. Blocks 97% radiant energy. Provides Rvalue of R4. Cost is about double that of Tyvek house wrap.

3) Micro E- for attics/roof: Aluminum facing 1/8" thick. Placed between joists, easy to install stapled with tabs. Rep. claims this will reduce the temperature of the attic between 30- 40 degrees! Cost is close to the house wrap.


If these work, they sound like they could be very beneficial in the long run. The initial cost (I am guessing) may be around 4-5,000 to install all of these. Which seems low to me for improvement on effeciency. They may produce good returns by lower heating/cooling costs over the next many years.

Have any of you used/installed these products? Does is seem to be worth the initial expense?

thanks

[Shophound]

Has a load calculation been performed for this home? With the possible inclusion of the products you've described above...was the six ton figure arrived at with those materials in mind? Offhand six tons seems a bit much for 3,500 square feet, but I can't see the house plan or architecture from here.

How about your window choices? Have you considered radiant barrier roof decking vs. the other product mentioned above? Easier to apply...the radiant barrier is already part of the deck. Once the rafters are sheathed with decking, the radiant barrier is in place and goes to work immediately.

If the length of the house runs north/south (broadest wall areas of the house facing east and west), I could see some benefit from the low E house wrap if both facades will receive considerable solar exposure in summer. If either facade is deeply shaded, maybe not. Hard to give east and west facades enough shade from dawn to mid-morning, and from mid-afternoon to sunset without very broad overhangs, patio covers, trellises, shade trees, etc.

The caveat for any of these products you are considering to work at maximum benefit is correct installation techniques applied. Same goes for your HVAC system and ductwork. You can have the highest end, most highly lauded energy saving technologies in place, but if they were not selected and installed with care, full benefit will be diminished.

[teddy bear]

Any concerns about IAQ-fresh ventilation and house tightness? Regards TB

[badtlc]

Those are nice but it is all going to depend on the quality of the whole house. Those nice upgrades will still be meaningless if your builder doesn't seal the windows properly or you have cheap windows to begin with. The color of the house, color of the roof (and material), and properly tinted west side windows would also be great additions.

[energy_rater_La]

3) Micro E- for attics/roof: Aluminum facing 1/8" thick. Placed between joists, easy to install stapled with tabs. Rep. claims this will reduce the temperature of the attic between 30- 40 degrees! Cost is close to the house wrap.

A better choice would be a radiant barrier plywood or osb
techshiels or solarply.
this is a roof decking with rb already applied.
in adding a rb under the decking you are paying for one area to be worked two times.
rb decking includes both steps in one application.

low e windows are a good investment.

best of luck with your build.

[energy_rater_La]

3) Micro E- for attics/roof: Aluminum facing 1/8" thick. Placed between joists, easy to install stapled with tabs. Rep. claims this will reduce the temperature of the attic between 30- 40 degrees! Cost is close to the house wrap.

A better choice would be a radiant barrier plywood or osb
techshiels or solarply.
this is a roof decking with rb already applied.
in adding a rb under the decking you are paying for one area to be worked two times.
rb decking includes both steps in one application.

low e windows are a good investment.

best of luck with your build.

[mbarson]

If the back of the house faces west you are off to a bad start, minimum west exposure is best. Solar exposure of the windows adds the most heat gain. Shading of the windows works best. Insulate attic to R 50+. Infiltration is a huge energy robber. Have the house built to Energy Star standards or better, it requires actual testing to document performance. House wrap is generally for a water resistive barrier that will breath and let moisture out. The aluminum coating on the low e house wrap may trap moisture and cause damage like the EIFS systems did, do some more research. Building it tight and ventilate right. Go to http://www.natresnet.org/ find a rater in your area and discuss you needs, you will get an unbiased opinion and not a salesman's pitch. The are many considerations when building a energy efficient home so take your time to do it correctly and you will enjoy the added comfort and energy efficiency you desire. R value is how slow heat is transmitted through a material, I doubt house wrap has any R value. Don't go by "effective R value" thats just a sales line. R 3 is the slab is minimal, go R 10+. Make sure to do the walls also.

[beenthere]

Check into open cell insulation.

Doesn't sound like a very energy efficient home, if you need a 6 ton WF.

[gonefishin]

If the back of the house faces west you are off to a bad start, minimum west exposure is best. Solar exposure of the windows adds the most heat gain.


The Back of the house will face the west however there is a large mature woods directly behind the house.

Insulate attic to R 50+. HOw would you reccommend this?


Infiltration is a huge energy robber. Have the house built to Energy Star standards or better, it requires actual testing to document performance. House wrap is generally for a water resistive barrier that will breath and let moisture out. The aluminum coating on the low e house wrap may trap moisture and cause damage like the EIFS systems did, do some more research. Building it tight and ventilate right. Go to http://www.natresnet.org/ find a rater in your area and discuss you needs, you will get an unbiased opinion and not a salesman's pitch. The are many considerations when building a energy efficient home so take your time to do it correctly and you will enjoy the added comfort and energy efficiency you desire. R value is how slow heat is transmitted through a material, I doubt house wrap has any R value. Don't go by "effective R value" thats just


a sales line. R 3 is the slab is minimal, go R 10+. Make sure to do the walls also.

How would you recommend R10 in the basement? What material for the walls?


I will look at the natresnet.org site and talk with someone there.
Thank you for your reply.

[gonefishin]

Any concerns about IAQ-fresh ventilation and house tightness? Regards TB

No, we have spent over a year checking out builders and found one who is highly praised. I have seen a number of his new construction houses and I dont have any concerns with the tighness of the house. Especially around the windows.

[gonefishin]

Those are nice but it is all going to depend on the quality of the whole house. Those nice upgrades will still be meaningless if your builder doesn't seal the windows properly or you have cheap windows to begin with. The color of the house, color of the roof (and material), and properly tinted west side windows would also be great additions.

I agree. I believe that the construction will be very well done. The builder has an excellent reputation.

We are deciding on Jeld-Wen vinyl low e windows or Anderson 200's. Do you have a preference? The back of the house faces west but there is a large woods just behind the house

[gonefishin]

Has a load calculation been performed for this home? With the possible inclusion of the products you've described above...was the six ton figure arrived at with those materials in mind? Offhand six tons seems a bit much for 3,500 square feet, but I can't see the house plan or architecture from here.

I have found a separate company who specializes in Geothermal. They sized the house with my blueprints and said that a 5 ton would work however if we finish the basement (2100 sq foot) later, or add a pool, the 6 ton would not have any problems. I have also worked this out with the builder that the same company that will install the field loops and install the WF will also do all duct work. This made sense to me since I didnt want the builder blaming any future problems on the duct work or vice versa. This company will be fully responsible for both. They also have an excellent reputation and do things correctly.


How about your window choices? This is either Jeld-Wen low e or Anderson 200's. Do you have any advice on each one. Andersons are 2600 more expensive.

Have you considered radiant barrier roof decking vs. the other product mentioned above? Easier to apply...the radiant barrier is already part of the deck. Once the rafters are sheathed with decking, the radiant barrier is in place and goes to work immediately.

This, no. I will look into this. I am very interested in this.


If the length of the house runs north/south (broadest wall areas of the house facing east and west), I could see some benefit from the low E house wrap if both facades will receive considerable solar exposure in summer. If either facade is deeply shaded, maybe not. Hard to give east and west facades enough shade from dawn to mid-morning, and from mid-afternoon to sunset without very broad overhangs, patio covers, trellises, shade trees, etc.

The caveat for any of these products you are considering to work at maximum benefit is correct installation techniques applied. Same goes for your HVAC system and ductwork. You can have the highest end, most highly lauded energy saving technologies in place, but if they were not selected and installed with care, full benefit will be diminished.

Excellent point. I have spent a great deal of time researching and checking on both our builder and the company installing the geothermal. I do not have concerns with the quality of their work. I know they will be done correctly. I am now looking for ways to improve on effeciency.thank you for your help

[beenthere]

If your house is going to be energy efficient. You shouldn't need more then 4 tons for that 3500 sq ft.

Sizing for the pool makes the 6 ton more of an energy hog when its not also heating the pool.

[teddy bear]

No, we have spent over a year checking out builders and found one who is highly praised. I have seen a number of his new construction houses and I dont have any concerns with the tighness of the house. Especially around the windows.

I was refering to the fact as houses are built tigher, the amount of fresh air infiltrating the declines to the point were most IAQ experts suggest fresh air ventilation be mechanically controlled. Many of the poster on this forum do not support mechanical fresh air ventilation. I do. In addition, green grass climates have enough wet cool weather that well insulated homes do not have enough cooling load to remove the moisture of the occupants and fresh air to maintain <50RH. Regards TB

[beenthere]

its not that we don't support mechanical ventilation. Just don't push it when it is not needed.

A 2000 sq ft house with 4 occupants needs more fresh air, then a 3500 sq ft house with only 2 occupants.

So the larger house may be tighter, and still not need mechanical ventilation.

Should he allow provisions for it, sure.

But if he needs 5 to 6 tons for it, its not all that tight.

[gonefishin]

I was refering to the fact as houses are built tigher, the amount of fresh air infiltrating the declines to the point were most IAQ experts suggest fresh air ventilation be mechanically controlled. Many of the poster on this forum do not support mechanical fresh air ventilation. I do. In addition, green grass climates have enough wet cool weather that well insulated homes do not have enough cooling load to remove the moisture of the occupants and fresh air to maintain <50RH. Regards TB

I made another post today. I am interested in the ICF reward wall system. The people I spoke with today use this and they do use a heat/air exchanger near the furnace to circulate outside air. I would not have a problem with this either. I just do not know enough about this. What do you mean a cooling load to remove moisture?

thanks again

[hangfirew8]

What do you mean a cooling load to remove moisture?

If the A/C doesn't have to run much to cool the house, it won't dehumidify much.

Typical problem in humid areas in Spring.

-HF

[energy_rater_La]

have you checked into SIPS building?
IMO this is by far the more superior building system.
SIPS panels are osb on both sides with foam sandwiched between.
No thermal loss due to framing members for a continous R-value.
Stick framed homes have 20 to 30&#37; of walls that are wood only
depending on framing methods. SIPS eliminates these areas where
studs lessen overall wall insulation.
SIPS panels for walls, floors, ceiling or roof installs are available, in
both 4" and 6" thickness.

I've tested (blower door tests)on many of these homes (sips, icf, stick built) and find SIPS to be the 'tighter' of the three.
In a 'tighter' house hvac load is reduced. I think that ICF has a hvac sizing and that SIPS also advocates proper sizing of system.
The savings of smaller properly sized hvac system will allow you to spend that $$
on other efficiency choices.

If your home is 'tight' meaning that the air changes per hour are less than .25 ach
you will need to add make up air. Otherwise your home will have the potential for many
IAQ issues, along with health issues.

Many people do not understand the need for fresh air because the homes & the ductwork are not tested for leakage. A home that has a lot of air infiltration will
not need fresh air, because the house will suck air in through the many leakage areas.
Once these leakage areas are sealed, then adding fresh air allows you to filter, and dehumidify the air before it enters the home.

I hear a lot of folks saying that their house is tight..but the fact is that you don't know
until it is tested.
Also in my area I find lots of duct leakage. In new construction
1.5 to 2 tons of leakage is not uncommon. With proper sealing methods duct leakage can be reduced to 10%. Companies like Comfort Institute promote 'the house as a system' which incorperates all the componets working together.

Many of the hvac companies that I work with had never tested their ductwork.
For them to understand the testing methods and find the areas of leakage made
it much easier to achieve lesser duct leakage amounts.

Also if you can locate your ductwork in the conditoned space leakage becomes a non issue, and is a great savings.
(anyone ever play around with Man J and customize the inputs to include ducts in conditoned space??)

I like Jeldwen windows..mostly because it is an affordable window that is well made
..and of course it tests well. Do invest in the low e.


Best of luck to you and congrats on building better.

[teddy bear]

I made another post today. I am interested in the ICF reward wall system. The people I spoke with today use this and they do use a heat/air exchanger near the furnace to circulate outside air. I would not have a problem with this either. I just do not know enough about this. What do you mean a cooling load to remove moisture?

thanks again

Just did another post explaining the concept. I have a well insulated home that has required very little a/c so far this year dispite many 85^F days. I remove 30-50 pints of water each day to maintain <50%RH. I did not start my dehumidifier until my basement was+70%RH and the mainfloor was +60%RH. That waas about 3 weeks ago. Find my previous post with data graphs. Today Madison ws 85^F, 65%RH, my house is 76^F, 50%RH with very little a/c. I will post the data next week. MY flaw is that I do not provide mechanical fresh air, only a cracked window plus building imperfections. A cracked window is not enough fresh air when the home is occupied. I will correct soon. Regards TB

[gonefishin]

[QUOTE=energy_rater_La;1923068]have you checked into SIPS building?
IMO this is by far the more superior building system.
SIPS panels are osb on both sides with foam sandwiched between.
No thermal loss due to framing members for a continous R-value.
Stick framed homes have 20 to 30% of walls that are wood only
depending on framing methods. SIPS eliminates these areas where
studs lessen overall wall insulation.
SIPS panels for walls, floors, ceiling or roof installs are available, in
both 4" and 6" thickness.



I have checked into SIPS building materials. IF it does what is says, it looks very impressive. However, this would not be a good fit for us what we are doing currently. I cannot bring in a totally new construction method and not step on my builders toes. The ICF is a little different. I Like the fact that these ways of building are far superior to what is done traditionally and I am willing to change my way of thinking, I just have to help my builder do the same.
thanks for the comments.