Insulated form construction

[Restrain]

Down here in Texas, the problem is not cold but heat. But there are still changes in building styles, the newer one being insulated forms, essentially foam panels. Coupled with such items as geothermal HVAC and other forms of insulation, these essentially make a home that can have air turnover of less than 1 per day. The good news is that the home is very energy efficient. The bad news is that it is a perfect breeding ground for mold and viruses that like greenhouse situations.

Any observed market differentials for these homes or are they too new to have more than an observed cost differential?

Roger

 

[Steve Owen]

As a general rule, anything that will help you with cold, will also help you with heat. (Technically, there is no such thing as cold, anyway. What you are trying to do is slow down the transfer of heat.)

I would want below grade insulation on any construction I was building on a slab, berm or basement. Up here in Missouri it's somewhat more important, or maybe not. Anyway, I have rarely, if ever, made any adjustment for insulation. First, construction practices are pretty universal for new homes. Secondly, when something is unusual, the market often either doesn't know about it or doesn't care.

I think you could make an argument that extra thick outer walls, extra deep attic insulation, blue board for basements or slabs, and similar kinds of things are worth more. However, I've never found the market data to back it up. (I believe I have occaisionally made a small adjustment for something like thick walls, but I was a little nervous about it.) When I appraise berms, I try to find other berms for comps, regardless of how far I have to go, or how far back in time. That way you don't have to worry about the adjustment.

Now HVAC is a different matter. In my market, duel fuel, ground source heat pumps, and zoned heating and cooling can all add value. And, market data will give a pretty good indication of that.

Well, I hope I didn't get too far off subject. If there is mold in the house, or strange smells, that is a definite downer as far as most buyers are concerned. But, I've never heard of a house bringing less just because it was tight.

 

[Richard Carlsen]

This is a problem that has its origins in the fuel crisis of the 70's. People wanted more efficiency for their homes and use less heating oil as prices skyrocketed.

Along come Tyvek, replacement windows, foam air sealer, new building techniques, hi efficiency furnaces that burn outside air and forced draft venting, etc. Suddenly that old draft box of a house is air tight and efficient. And all new houses didn't have to be bermed houses now.

At the same time as efficiency rose, interior air quality decreased because of the lack of air exchange. Is it any wonder that we have had a 40% or so rise in respiratory illness in children in the same time?

Here in Michigan when you build your very energy efficient house the way they want you to, you now have to run about a 4 inch PVC line into your cold air return to bring outside fresh air into your system. If you have a hot water baseboard system, you spend about $2500 on an air exchanger.

It has seemed absurd to me that one would spend an extra $1500 to $2000 for a 94-98% efficient furnace burning outside air only to have to bring fresh air from the outside directly into the cold air system. You have immediately lowered your overall efficiency by doing so. Why not spend less money on an 80-85% system that burns inside air and uses a forced draft vent? This way, when the furnace burns and forces the draft, you will be creating a slight vacuum in the house and there will be infiltration of outside fresh air all over the house in small amounts? I would think that this is a healthier way of living that in a tightly sealed, highly efficient house.

I think mold is not really the main problem. Dehumidifiers can control that. The main problem is living in the old, stale air inside the house week after week. Sure your heating bills are lower but your doctor bills go up.

I don't know that the public is up on this connection yet and I cannot measure anything in my market. On the contrary, up here where I've seen the temperature drop to -41, there is a premium and pride on the houses energy efficiency. The stars are still in their eyes over the low fuel bills.

 

[Farm Gal]

Been studying this type of construction for years. Good idea IF properly designed. Built several myself. real proud of the "Energy-Star" rating we earned!! You know hte little green/blue globe logo!

You are correct in that humidity buildup is a concern, but only if not handled correctly. Properly venting shower and laundry areas, and dehumidifiers can handle this very nicely. Ever slept in a vented versus closed up tent in cold weather? Same effect!

Heat exchangers are a better idea than pumping cold/hot outside air 'into' the system, and if you wind up 80%+/- efficient you are still waaay ahead on the conditioning-cost game because the rest of the house is ultra-efficient.

Indoor air polution is normally not the result of human occupancy but rather the materials used to construct and (worse) the possessions we place within the walls. Ever check the offgassing from a typical carpet during it's first year of life? Scary!!!!!

Detoxifying can be largely handled through natural means: a single spider plant can remove most of the toxins produced in a 12 x 13 foot room. Getting an air quality specialist or self educating is a very good idea. I have a black thumb but even I can keep spiderplants alive.

I have hard flooring and minimal pressboard products in MY home. and can tell when I go in someplace they don't.

 

[Tejus]

Roger,

You need to be careful when referring to ICF's (Insulated Concrete Forms). There are many products and they are not the same. I recently built an ICF and investigated them thoroughly. There is a good 4 page summary of ICF manufacturers and products at www.dulley.com, Update Bulletin 507.

As you stated, many of the ICF's are like styrofoam and do not allow air to pass thru. However, there is one ICF (FasWall, made from recycled wood chips and cement) designed to allow air to pass thru. This should prevent mold and stale air. This is one of many reasons I chose FasWall over the other ICF's and conventional frame construction.

I've also investigated geothermal heating/cooling. Sounds like a good idea, but I'm concerned when the geothermal dealer/installer states a homeowner is better off with the new high efficiency heat pumps.

I've talked to several homeowners who replaced their older heat pumps with geothermal and obtained big savings. After further discussion, they also disclosed their old air ducts were leaking and had to be replaced and their old heat pumps were not efficient. The homeowner would have seen the same savings if they had replaced their old system with a new heat pump and saved the $0000's drilling the geothermal holes.

 

[Verne Hebert]

I love it when you "guys" start talking like this!

First the air exchange issue. The UBC mandates a minimum air exchange...............and this is not in compliance.

I was in Tucson a few years ago when the ICU where coming of their own. Habitat for Humanity in this area is doing alot of construction and research in that climate. You might want to call them. I enjoyed looking at some of their homes, both complete and in progress.

Up here in God's country, I am seeing a lot more ICU use; but it is generally in the higher construction and it is difficult to isolate the form use itself. But my gut tells me, as long as it is insulated, nobody really cares how. There is a definite adjustment here for all types of heating, and ground source heat pumps and in-floor radiant heat (gas or propane fired) command a good hit-considered very desirable by the market.

In the spec market and owner-builder market, the ICU's are used because they are user friendly--anybody with limited skills can (often) build an acceptable foundation.