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Ideas for new construction

Posted by dt1234 (My Page) on
Sat, Apr 5, 08 at 4:20

We are building a new home. Underground plumbing and the foundation is already poured.

Is there anything i can still do at this stage to reduce our energy usage that really works well and reliably and is not very expensive? Anything I invest in i should be able to see a return within 10 years because I may sell the home in that time.

Ideas?

This is in sunny Texas.


Follow-Up Postings:

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RE: Ideas for new construction

I presume the house is slab foundation - no basement?

Here are some things we did:

Use 2x6 framing to provide deeper insulation cavity

Caulked and foamed the interior of the home. Every seam between joist sections, at the top and bottom plates, around windows and doors. Any small cavities where the cellulose would not stick or could get be sprayed in we used spray foam. My house took over 8 cases (96 cans) of spray foam just for nooks and crannies. Probably an equivalent number of caulk tubes.

If you have fireplaces, make sure they insulate around the opening as best they can. Our insulation people were horrible in that area (they said it was the firplace people's job to insulate around the fP. FP people said it was the insulation companies responsibility) - so I insulated it myself.

Used dense pack spray cellulose insulation in wall cavities and attic. If I had the money, I would have used spray foam. Put an extra thick layer of insulation in the attic.

Purchase the most energy efficient windows and doors your budget will allow.

Spend a little extra and buy the most energy efficient HVAC system your budget will allow. It may not be too late to consider geothermal, but he cost delta is not small. I have a GT system - my cooling bill for 1 month on a 6000 sq ft house that did not have the attic insulation yet was less than $200 - amazing.


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RE: Ideas for new construction

Ditto on Geo!

SR


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RE: Ideas for new construction

sniffdogg, thanks for the great advice. Geothermal is very expensive right?


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RE: Ideas for new construction

A light colored roof will keep the house cooler.

Plant deciduous trees to shelter south and west.

If still possible, minimize your windows especially on the north, but also east and west. Plan for overhangs, rolldown shades or an arbor to shade the south windows.

Compact fluorescent bulbs are 4 times as efficient as incandescent.

Induction cooktops are twice as efficient as radiant electric or gas.

Solar hot water will pay for itself in less than 5 years. Integrated hot water is nifty, but pricey.

The slab foundation will act as a heat sink in the summer and a heat source in the winter, if you don't insulate it with carpet or wood. Use a flooring material that conducts heat such as tile, stone, or polished concrete. My tile floors are 60 degrees in the winter and 65 degrees in the summer all by themselves!

Here is a link that might be useful: Energy Efficient Construction Techniques


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RE: Ideas for new construction

dt

The cost of geothermal has a lot of vaiables to it and the breakeven point has much to do with the cost of the energy of whatever alternative HVAC systems you are looking at - so it is hard to say.

In my case I have 12 tons of HVAC in the house - it was $15,000 more for the 3 heat pumps and internal plumbing as compared to a high efficiency LP has heating system and air conditioner units. Then you need to add on the cost of the loop system outside which can be wells, a large pit, or a pond if you happen to have one. For me - this cost was very high (more than we expected) since we built on a mountain slope and hit a lot of rock.

As one of the other posters mentioned, you might be better off taking that additional cost and investing in better insulation, windows, doors, etc. However, I still recommend getting a few estimates on the GT since your site and specific implementation might not be as costly as mine was. I actually considered this (I had a chance to back out of the GT installation) but the extra cost for going from cellulose insulation to foam was more than the extra cost for the loop field, and at that time there was no way of changing anything else like windows & doors since they were already in.

You also have to think about how long you are going to be in the house and where you think energy costs are going to be in the future. Since I built my home with a 20 year plan and my only alternative heat was LP gas (and we all know where that price is going) the GT still made sense even with the extra un-anticipated cost.

I think if your time horizon is greater than 7 to 10 years, GT is attractive. If it is less than 7 to 10 years, other options like HE heat pumps and better insulation packages might make more sense.


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RE: Ideas for new construction

Insulate as much as possible, you will get your money back for sure. Make sure windows have sufficient overhang to prevent excessive heat gain in the summer. Consider solar hotwater heating. Look into passive solar heating options.

Here is a link that might be useful: Solar heating


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RE: Ideas for new construction

You are in a hot enough area that you should be using a heat recovery unit on your AC. Lets you use a 13 SEER unit at great install savings but still run at a high efficiency level...plus get free domestic hot water. A $30-50 month saving on electricity is usual on an average size house. Much faster payback than solar.


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RE: Ideas for new construction

One of the greatest energy conservation devices is so low tech as to generally go totally unnoticed by the general public.

At each entryway have an inner and outer door. This could take the form of a short 5' vestibule hallway with an exterior door and inner door, or a hallway between a semi-detached garage and the main structure with an exterior door from a walkway into the hall way, or it could be a mud room with a door at each end.

However you configure it, the end result is that it creates an air lock where the outer door is closed before the inner door is opened so you do not have a blast of wind driven exterior air blowing into your climate controlled space every time the door is opened.

You go through this type of entrance a dozen times a day while shopping and never give it a moments thought, but you can rest assured the commercial architect that designed the malls, supermarkets and large stores gave it considerable thought.


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RE: Ideas for new construction

Re-visiting your original post...Things that pay back fast... heat recovery unit is a must. It allows you to use a cheaper heat pump unit (SEER 13, r22 system...saving about $2000) and wind up with something in the SEER 16 operating range. In Texas as well as Florida, solar is an enormous waste of money. Wait, you say, "Solar heat is free"...Yes, but you are ALREADY moving a bunch of heat around with your A/C system. It only makes sense to 'put it in the hot water system'. GT will not provide sufficient savings as opposed to a good HRU equipped heat pump. The system in my house gives us a $120-130 a month power bill...roughly the same as people we know with GT but at a cost of $5000 as opposed to $30000. No-brainer to me......


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RE: Ideas for new construction

I like the thought of the waste heat recovery unit..adding one to a lower seer unit that is a few years old and in good working order, not a bad plan at all. I do not see however why a person would want to skimp on the efficiency of a heat pump just for 'free' hot water. If the climate is mild and the unit isn't running than how free is the water? I think the total additional installation cost and unit cost needs to be figured in to get the 16seer for 13 seer a/c heat pump price.
Do some research on heat pump hot water heaters same concept as your heat pump except they heat the water and come in many different flavors. You can get stand alone units that hook up to a conventional hot water heater or ones that are part of the heater themselves. There are units with high and low toggle switches that on high will run fans and actually cool an area, your basement or garage etc. If you live in a cool climate you can duct them to the garage so you don't have to worry about the unit freezing in the winter. From the research I have done on heat pump water heaters they consume about 5amps @ 220v or 10-15amps at 120v. Here are some links.

http://www.aceee.org/consumerguide/waterheating.htm
http://www.nyletherm.com/waterheating.htm


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RE: Ideas for new construction

Mo, you don't 'skimp on efficiency' using the 13 SEER unit. The HRU adds a few points of efficiency to any unit it hooks up to, however, as you get into the higher efficiency units, I understand there is less heat available for the HRU to use hence they don't get used on SEER 14 or greater. My experience is that here in Cent FL, on an 88 degree day, my 13 SEER unit has 195 degree hot gas exiting the compressor. HRU mfgs state that temp should be 180+ for the system to work. The end result is the a/c's performance is around 15 SEER or so. This comes from the hot gas being 'shrunk' by the HRU and the accompanying drop in compressor head pressure (and lower current draw). Add the energy savings of the water heater being off and the total effective SEER is probably around 18-19. Of course when the heat pump's not running you get no free hot water but a non-HRU high efficiency a/c wouldn't be saving you any money at that time either. I have an 80 gallon water heater that serves as the storage tank and backup heat source. The heat pump water heaters are way better than resistance or gas heaters but still use a fair amount of power. The HRU's circulator pump only draws about .3 amps. Actually, in the winter time the HRU makes your heat pump into a heat pump water heater. Although the system will run longer to heat the house, in the final analysis it's still cheaper since the water is heated more efficiently than by the resistance water heater.


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