| Author | Message | ||
     Scottorious |
Ok, we all know the benefits of thermal mass and using the ground as a wonderful heat sink. Just for the sake of experimenting I have come up with an interesting experiment. I have a rather small house and I live alone so I think I can get away with this. I have posted an statement to all friends and family asking for donations of empty milk jugs. I will clean and fill these milk jugs with water to the tune of near 1000 or more of them hopefully. I will attempt to place them all throughout the house in areas out of the direct sunlight. My plan is to use them as thermal mass and see exactly how much I could offset the running of the AC in the summer. Now clearly I will still have to potentially run the AC the same amount to remove the heat but I have 3 plans for that. Plan 1: If the nighttime low will cool enough to assist in cooling my thermal mass I can open my windows and blow all the heat back out. Plan 2: This is wear the stone age part comes in, I could store a reserve of 200 or so milk jugs in the basement on the concrete floor where they would release their heat into the concrete and hopefully equalize around ground temp. I could manually make 100 trips or maybe 50 if I could devise a way to easily carry 2 in each hand. I would then rotate my thermal mass slowly and take 200 warm jugs down and bring 200 cool jugs back up. Plan 3: I signed up for a program with my power company called power smart pricing where I will pay market price for power which changes by the hour. Last year on July 25th the cost of one KWH between 3 and 4 PM was over 11 cents however the cost of one KWH between 3 and 4 AM was at 2.5 cents. This means that I could pre-cool my thermal mass for around 25 percent of the price I might pay during the more demanding parts of the day. Where are any large flaws anyone sees with this idea. In some ways it relies on me being single and young and especially cheap. | ||
| Ourdee |
Opening windows at night lets humidity back into the house making it feel warmer in there. It would be easier to pump liquid than carry it in containers. A bigger saving could be realized by only air conditioning and living in one room. Bathroom would be the cheap choice. Insulate it and set up a cot to sleep on in there. Better, make a cold room in the basement and live in it. Leave the AC off in the rest of the house and the windows open. When I was single I lived in a 6000 SF house. I Cooled one room on the first floor with one window AC and lived in it during the work week. I used a bathroom on the third floor so that the steam from the tub didn't get near my cool room. I have and still use silver mylar film on windows to keep sun/heat out of my house. Black-out curtains finnish the job and dampen sound. Cameras and a monitor let me know what is outside, if I want to know. Look into an attic fan to lower the temperature on your ceilings. A whole house fan may be worth looking into. It sucks the air out of the house forcing it through the attic. | ||
| Mr_grumpy |
You'll be pushing more heat into your house running around with your milk jugs of water than they could ever possibly offset. 1000 milk jugs, they're 1 litre here so that's a ton of water. However, it'll keep you fit & save a fortune in gym subscription. If you have a basement & you're not bothered to see outside, live in it, it's the best insulated part of your house. I did suggest the idea to my dear wife once in the interests of economy. Once the ballistic trajectory had come back down to a hearable level I began to discern words like "caveman" & "ice age" coming fom her sweet mouth amongst other expletives with which I shall not bother you. Seriously, the best thing you can do is make sure that the loft/roof/crawlspace is WELL insulated, most heat enters & leaves through the roof. Windows on the sunny side of the house, external shutters to stop the sun coming in in the summer & the wind & rain in the winter. Check out how houses were built over the centuries & use the old methods with new tech. | ||
| Doz |
"Ballistic Trajectory" is not a concern of Mr. Scottorious....yet. Unless he finds a nice cavewoman. | ||
| Scottorious |
I have considered moving into the basement however that would be not much fun for my dog as he would have no windows to look out all day. So because I do have a dog(labrador) that would much prefer 0 degrees to 80 degrees I can't fully abandon the main floor. I also would like to do this to better understand where i could add thermal mass while renovating in the future. My windows do have shades. So maybe I scratch the moving the jugs up and down stairs and just stick with using cheap electricity at night to pre-cool my "thermal battery" and hope I can glide all day. Considering that used milk jugs are free as my family and friends donate them and water could be anywhere from free out of the hand pump to cheap from municipal water I don't see that I'm out anything if it doesn't work according to plan. | ||
| Kenm123t |
How Cold Is the ground water ? | ||
| Two_seasons |
Another consideration is all the condensation from the outside of the milk jugs. What will you do with that water? Better to have a super efficient ac unit. We went from a 9 seer to a 17 seer. What a difference in $$. And ah, the quietness of the new unit too. Worth every penny. | ||
| Cityxslicker |
we did an off grid fridge when we were camping as kids (uncle was a science guy) You take a 5 gallon round bucket and a 3 gallon round bucket (both with lids) fill the bottom bit with beach sand, with a hole saw cut 3 inch holes randomly through the sides; wrap the bucket with a thick visqueen, place small bucket into other bucket; fill the excess with beach sand. Pour water into the larger bucket Put your WRAPPED food in the smaller container, put both lids on, place in the shade viola as the water evaporates from the sand - it gets cold - (and heavy ! ) works like a charm Now, You could do that same concept with your floor, or an interior wall ..... It would be an interesting experiment. He was always saying that you could do the same with cinder blocks, with sand down the center of them | ||
| Sifo |
Plain old dry wall has quite a bit of thermal mass. I have doubts that water jugs will have any measurable benefit. Making sure that the attic has enough insulation can make a big difference and is cheap to DIY. Also make sure that the attic has acquitted ventilation and that the insulation doesn't block air flow from the vents in the eves. There are real geothermal options available that work, but it sounds like you are trying for something cheap. Some things are more suitable than others, depending on details of the site and building. One of the difficulties of using simple thermal mass is that you need to be willing to live with it down right cold at night and mornings at times, and evenings can still wind up warm. I've stayed on Maui where the climate allows for that quite nicely. Down below 50 at night, near 90 in the afternoon. No hear or AC at all, just large windows with huge eves that allow windows to be open even when raining with a good breeze. BTW, keep in mind that you are talking about roughly 8,330 pounds of water that you plan on storing. | ||
| Gentleman_jon |
This is not a good idea, simply put. Reason is that "thermal mass" alone is only a very small part of the equation here. You need to have a way to exchange the difference in temperature of the water, and the air in your house. Possibly the worst way of doing this is putting cold water in a milk jug, which has a very low surface area to volume, and would be even worse when the jug are grouped together. Not to mention the insulating properties of the plastic jug itself. So the jugs won't get very cool at night, and they won't cool off the rooms during the day. I agree with Mr. Grumpy that the only things you will get is a warmer house and a lot of exercise. This is perhaps why this system has not been invented previously. Ken has the germ of an idea when he asks about the ground water temp. You could pump water into a coil in a subterranean cistern filled with ground water, or a well if the water is cold relative to the air temp in the house. Then run the water through a series of car radiators in your house, with air blown through them by electric fans. This would blow cold air into your rooms, and eliminate the need to carry a ton of water up and down stairs every day. An attic fan to exhaust the hot air would be good, and as mentioned above, insulation in the attic is a good idea too. Frankly the high efficiency a/c unit and effective thermal management of heat gain at your windows sounds like the best idea to this old architect. I do applaud you for some very original thinking here though.  | ||
| Sifo |
You could pump water into a coil in a subterranean cistern filled with ground water, or a well if the water is cold relative to the air temp in the house. Then run the water through a series of car radiators in your house, with air blown through them by electric fans. This would blow cold air into your rooms, and eliminate the need to carry a ton of water up and down stairs every day. You can have the heat exchanger built right into the existing forced air heating/cooling unit. My brother has this in his house for heating with a wood fired boiler in an out building. Very nice set up. The attic fan (often called a whole house fan) is very old technology. My in-laws had that installed in their home many years ago. They have recently found out that correct insulation and a modern AC system is cheaper than running the fan. The worked well long ago when insulation was poorly done and AC didn't exist. | ||
| Johnnylunchbox |
There are hundreds of designs out there for something like this. This one is actually rather complicated. | ||
| Scottorious |
Coils, pumps, cisterns, pipes all have costs and have the ability to break down needing expensive repairs or replacement. Adding thermal mass in the right areas can passively help moderate temperature(or so I thought). So if I scratch the whole idea of moving jugs up and downstairs and just position them throughout the house with plenty of airspace around each one and just use cheap electricity at 3 AM to run the AC (which is already a high efficiency model) which then would allow the high thermal mass to at least slow the increase of the ambient air temp in the house. If 15,000 pounds of water requires 15,000 BTU's to raise it one degree even if they only absorb 1 degree an hour that is still equal to a 15,000 btu/hr window AC. I'm currently running an experiment with a temp probe in the center of a plastic jug of water which came out of the tap at 48F. I have a probe on the outside of the jug touching the plastic and another just taking ambient air temp. My picaxe is logging this data every minute into excel and I will show my data when the water reaches room temp which is currently 68F. | ||
| 86129squids |
Methinks it'll be another HOT summer... gotta factor in an insulation job into my upcoming remodeling, if at all possible. IIRC, most if not all improvements in this area are tax-deductible, so that would help immensely. | ||
| Scottorious |
I'm currently insulating my entire second floor, Using foil faced polyiso to achieve R39. 2x4 stud walls with 2 inch nailer running horizontally to break the thermal bridge. On the ceiling I'll be blowing in as much cellulose as will fit. | ||
| Scottorious |
 opening the windows is always an option if it looks like the temperature will drop to a comfortable level. I just wrapped up an experiment with a single gallon of water in a plastic jug. With my picaxe I logged data points at every minute for the last 3 hours to track how much heat a gallon might absorb just sitting in on a chair. The graph isn't perfect to read but the water started out at 48 degrees F which was from the tap. In 3 hours it rose in temperature to 58 degrees with the ambient air temp at a pretty consistent 68F. The other line that holds at 62F was a third temp probe that was just resting on the side of the jug. The probe in the water was roughly dead center of the jug. Raising 10 degrees in 3 hours absorbed 80 BTU. If this scaled up in the same manor that would be roughly 80,000 BTU in total or a bit over 26,000 BTU an hour. 26,000 BTU an hour seems like a nice help to the central air. I know in the summer it would be difficult to get water to 48 overnight. However I think the 20 degree temp difference could be achievable. Diurnal temp swings in July can be about 20 degrees. Just opening the windows late at night could feasibly remove a large portion of the heat boosted by the central air at off peak rates. | ||
| Kenm123t |
Jon and Scott I do this professionally We can cool your house with 48 deg water I prefer 42 but I live in the Fla swamps. All the formulas for cooling heating are well established Decisions needed are only in what equipment to use. Thermal mass is ok for heating but useless in controlling humidity. Remember total heat includes latent as well as sensible heat. Insulation and vapor barrier placement is critical to prevent mold and water damage to the structure. I make a very good living correcting these issues when members of the engineering community ignore the basic thermodynamics. They let the customer say I only want do this so ( fill in excuse for proper engineering here) so what I want to do is ok! Scott you need to do proper load calculation then based on the design of the house to choose system or systems. | ||
| Scottorious |
Agreed, the jugs of water would do nothing to dehumidify my house. Running the A/C for a period of time in the early morning hours would remove moisture. I could save a considerable amount of money if I could simply offset when I ran the A/C If the A/C ran for the exact same amount of time each day but I could do it at off peak times for less than half the cost per KWH money could be saved. | ||
| Kenm123t |
How big is the house and what is your price per KWh | ||
| Scottorious |
House is 1296 square feet. KWH prices are variable. I use a program called power smart pricing (powersmartpricing.org) and I pay rates that vary greatly. As an example I used a day in the heatwave we had last year. june 29 had prices as low as 1.9 cents per KWH which occured for 3 hours during the early morning. During peak demands prices jumped to 9 cents per KWH. here is the link to that graph. http://www.powersmartpricing.org/chart/?price_dt=6 /29/2012&display=table | ||
| Scottorious |
The summer is a wonderful time to use off demand power. They aren't going to slow production down much if any so early morning hours have power being produced that has to go somewhere. I'll gladly shift my usage to pay low prices. Using high mass that I have cooled significantly will hopefully help me out. | ||
| Sifo |
Have you gotten your water heater set up to only heat during off peak hours? A well insulated water heater should be fine doing this. | ||
| Scottorious |
I have an on demand water heater. Which is gas anyway. | ||
| Scottorious |
Ideally I would shower during off demand times anyway to reduce heat gain in the house. | ||
| Fast1075 |
I checked a couple of sites and they seem to indicate the ground water in Illinois is not quite cold enough for much use at around 57 degrees F. That would offer little latent control. Unless you live on the shores of Lake Michigan and are willing to invest a few hundred thou setting up a deep water drop pipe and pumps. The idea of basically living in a single room is not foreign to me, as I live in a studio. I installed a high efficiency mini split system. Variable speed and capacity. It is extremely economical. | ||
| Kenm123t |
Fast is correct a zoning system such as a Daikin VRV s with multiple ahus is the best way to go. The cost of the system less expensive than Rube Goldberg half way measures your electric rates even at peak prices will never pay back the cost of a large thermal mass system. It will never give you the results that you want. We pay 8 cents kwh and we rarely shut the A/C off but we use a heat recovery unit for hot water 6 of us 3500 sqft under air and we average$220 a month | ||
| Mr_grumpy |
Where we used to live in Brittany was an old farmhouse that we renovated. 3' thick earth walls & surface capture low temp geothermal heated floors. Nicest place I ever lived, the walls kept the place cool in the summer & warm tiled floors to walk on in the winter is glorious. Heat pump was giving 4-1 from a 200mē capture zone in the garden buried at about 1-1.5m. | ||
| Gentleman_jon |
Let's keep floor loads in mind as well. Milk in the USA tends to come in one gallon jugs that weigh about 8 1/2 lb.s full of water. Thus a thousand of those puppies will weigh over four tons, not one as Grumpy stated. (He used litre bottles as the basis for his calculations). Since the max floor load for a typical US house is 30 lbs per square foot, the total load for an 8x 10 room would be about one ton. See where I am coming from on this one? | ||
| Kenm123t |
SHOOOSH Jon don't tell him about floor deflection due to over loading. We want Blake to send us 4 pages of calcs  | ||
| Gentleman_jon |
Very excellent thinking. Ken!! It's not only thermal problems that we have to think of. I'm guessing you're thinking excess floor loading means pretty serious floor deflection. Milk jugs fall over, leak on floor, floods basement, creates perfect environment for mold, house gets condemned, torn down by county. Is that where you're coming from, bunky? Just the architect in me coming out. Promise it won't happen again. Serious. PS: Can't wait to see Blake's analysis, can you? |
