Energy Conservation tactics

I have recently started some upgrades to save on heating/cooling cost. Has anybody here put any radiant barriers up in their attic??? My house was built before radiat barrier technology was easily available. I cringed when I did a rough estimate on replacing the roof and roof decking or purchasing the long rolls of foil that would be stapled to the rafters. I found a radiant barrier paint by Shermin Willliams that claims it can stop up to 68% of the radiant heat from coming through your roof. The paint can be applied by a sprayer with a large tip that will allow the metalic particles to pass through. I can have the whole job done by a contractor for $1000 to $1200. Replacing the roof and decking would cost about$14,000 but can stop more radiant heat.

Has anybody used radiant barrier paint? If so have you noticed a temp drop in your attic?

My attic fans have died and I have ordered some solar powered ones. The panels are built into the domes but are adjustable for maximum sun exposure? I figure they will pay for themselves in 2 years. My neighbor has offered to build some high efficiency AC to DC converters and switching controls to still help out after the sun goes down and the temp is still high. the house has a mixed bag of passive and active ventilation.


The last idea is to replace my two gas water heaters with either 2 tankless gas water heaters or go with only one tankless with a capacity of 8+ gal/min with a 40 to 50 degree rise from inlet water temp. I read a white paper that does a trade off study between gas water heater and both types of tankless water heaters. The electric tankless is out because of the power requirements. The traditional gas water heater still wins out if you have 4 or more people using it. If you have 2 or less people then the tankless wins. I have researched solar but my deed restrictions prevent installations that can be seen from the street ( the direction by south facing roof faces). I am leaning more towards the tankless just because I hate the idea of having water heater in the attic. The tankless can easily be installed on a outer wall or in a walk in closet with appropriate vents to supply fresh air and take away the exhaust gases.

Again does anybody have a tankless system? Do you wish you installed a bigger one sometimes. I am thinking of getting two 7.4 gallon/minute ones. With a 45 degree rise I can still deliver just under 5 gallons/minute with each one

BB will likely jump in here as well

For the water heater the problem with tank less as it sounds like you already know they are les efficient then standing tank heaters, but have far less standby losses. Just going off the top of my head, but a regular cheap natural gas water heater might be 70% efficient, meaning 70% of that gas that is burned turns in to heated water. A tank less might be in the 80's and a condensing tank water heater might be in the 90's. But, the big but, you might be better off with a tank less if you don't use much water because less heat is lost during standby. If you use more water a good condensing water heater would be the way to go.

As for attic insulation I would just add insulation to get you up to about 24 inches, blown in is fine. A thermal barrier would be nice but the insulation will make more of an overall difference. I would have them cut a ridge vent in the roof and be done with it. You will get a lot more air movement with a ridge vent and would likely cost about the same and nothing to break over time.

sorry about the confusion.. When I talk about radiant barriers I am talking about the putting it on the roof rafters that support the exterior roof. I have been in a new house a few blocks away from mine with the new radiant barrier decking and the temp of the decking is 105 F measured. I measured it in my house and the decking temp was 145 F. that was pretty impressive.



thanks for the input. I have seen some of the tankless ER of 85 % with the lowest one I looked at about 60%.

Yes, I should have been clearer. What I understand radiant barriers to be, they are up against the back or underside of the roof reflecting the heat back up to the roof so it never gets in your attic in the first place. Is that correct?

I have heard that on older homes this isn't a good idea because it heats up the roofing material to a point that was never intended when the roofing material was made.

That's why I would suggest good insulation below the roof and above the ceiling of the top floor. A ridge vent will allow the heat to escape out naturally, an easy thing to do if you ever replace roofing.

that form of radiant barrier is what I am talking about. I have not heard of problem with composition shingles. If I had my way I would just replace my roof with aluminum roof when it comes time to replace it. But alas most people have a problem (ie home owners associations) when your house looks different from everyone elses. IMHO people are afraid to really think the request through and are afraid they will be questioned about their approval. I know about this stuff first hand since I am on the board. they did not like it that I voted for a deviation that they rejected and got even angrier when I refused to change my vote to make it a 3-0 rejection. At least my neighboor hood of 25 homes are not as bad as some that make you get permission to change out plants in your flowerbeds. I am coming to a conclusion that it I want to have an green energy home I will have to move out of the city limits.

The blown in insulation can make a big difference. I bought 10 bags from home depot to get free use of the blower and put it down the rear crawlspace in my house (its a 1/5 story so I have 3 small crawl spaces). Then I put insulation on the walls because it was only on the roof and my gas bill was the same this winter as it was in 2003 and we have turned the temp up a couple degrees and don't have it turn down during the day or at night anymore because my wife if home now with our newborn but the insulation managed to keep our bill level.
We didn't have any insulation in the walls so I drilled 2" holes at the top of each space in the walls of one room then blew the insulation in there and it made a big difference in that room.

Brock. I never heard of a condensing water heater so I googled it and found this tidbit.
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The most efficient gas-fired storage water heaters have energy factors ranging from 0.60 to 0.65, corresponding to estimated gas use below 250 therms/year. Condensing water heaters have energy factors as high as 0.86. The most efficient electric storage water heaters have energy factors ranging between 0.93 and 0.95, resulting in estimated annual energy use below 4,725 kWh/year. There is little difference between the most efficient electric resistance storage water heaters and the minimum efficiency standard. Fortunately, heat pump water heaters using less than half as much electricity as conventional electric resistance water heaters are becoming commercially available. If you use electricity for water heating, consider installing a heat pump water heater. Otherwise, look for the most efficient electric resistance unit in your size range.
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I need a new one. Now, where to find an efficient electric storage heater.

Don't know where to get them, but keep in mind electricity is usually quite a bit more expensive then natural gas. Here regular electricity is about 55% more then natural gas per BTU so even if an electric water heater is 95% efficient, it is still cheaper to heat water with a cheaper 65% efficient water heater.

And heat pump water heaters are fine unless you are heating your house, then you have to heat the house more to make up for the cold air they make heating the water. Great for summer or any time you need cooling in places it doesn't get to cold, but up here the energy saving in heat pumping you water heater would be offset by the additional energy needed to heat the home.

I have a Noritz tankless water heater that runs on gas. I live in a condo and the original water heater was mounted on the roof in a cabinet, as is now the Noritz, and this happens to be directly above one of the house bathrooms. If you're in that bathroom with the water heater over it and taking a hot shower the water heater sounds like a jet engine... very loud unit. I've been considering re-mounting it on vibration isolators and replacing the solid copper couplings with Teflon-lined flexible water lines to help reduce noise.