Comments on: Free Radiant Cooling – A Closer Look

By: Doug Jones

Doug Jones — Wed, 11 Nov 2009 07:55:37 +0000

It’s actually a bit better than you suggest- the area of the slab isn’t important, as long as the heat transfer is good. All you really need to know is the mass flow rate, temperature change, and heat capacity of the water. I calculate about 17,000 btu for warming 100 gal/day of water from 55 to 75 F (78 F is a bit optimistic, the slab would be too warm to cool the house much). Free cooling indeed!

By: Jim C

Jim C — Wed, 08 Jul 2009 04:30:10 +0000

Hi, I’m about to start on my Sip project in about a week, I’m kicking around the radiant cooling idea, has anyone implemented this locally in SE PA?

By: chad

chad — Mon, 24 Nov 2008 16:41:08 +0000

Interesting idea Paul. It would increase the complexity a bit as we would need separate loops most likely and two sets of pumps. Also, we don’t plan to have plants that require much watering so I don’t know how much cooling we’d get…

By: Paul Beaton

Paul Beaton — Sun, 23 Nov 2008 23:08:04 +0000

How about a in-floor (slab) radiant system that pulls hot water from a solar heater in the winter and from a large in-ground cistern in the summer used primarly for watering plants?

By: Red Green

Red Green — Mon, 13 Oct 2008 14:11:31 +0000

My thought was to lay in a 50′ by 50′ lattice at 10′ to 15′ below ground level and then to pipe it up into the housing using a very small motor. Once inside the house it would go through a radiator with a fan blowing through it. From there you could duct it just like a central air system. I am almost positve it would work in a low humidity setting, not so sure about higher humidity areas of the country though. Any thoughts?

By: Budget & Schedule Update Meeting with Brian the Builder | 100khouse.com

Budget & Schedule Update Meeting with Brian the Builder | 100khouse.com — Fri, 19 Sep 2008 18:26:30 +0000

[...] can do this with one boiler still that has two zones, but we will lose the ability to implement the free radiant cooling technique that I was really excited about testing out. Secondly, the open CFL lighting is not going to fly as [...]

By: Kevin Bourque

Kevin Bourque — Sat, 21 Jun 2008 22:38:21 +0000

Chad, you don’t need to worry about “spending a lot of money on more energy modeling” if you’re simply looking for answers about these “what-if” type questions. Use RETScreen. It’s a free energy project analysis software made by Natural Resources Canada (disclaimer: I’m one of the developers) that is made to answer these type of questions. RETScreen doesn’t require a huge number of inputs yet still gives you a good idea of the impact of potential changes (e.g. compare “less insulation, poorer windows, over double the lighting and took into account none of the passive cooling strategies” with your current strategy.)

I’d love to see a RETScreen study of the 110k house because then the files can be made available to everyone. Try it out at http://www.retscreen.net. We even have some research at our lab where they are using RETScreen to evaluate zero-energy homes, etc…

Kevin
PS – I also am part of the technical support team, so can help with some basic usage of the software. But please e-mail rets@nrcan.gc.ca for that because my wife and I are expecting a baby any day now, so I’ll be away from work for a few days.

By: chad

chad — Mon, 16 Jun 2008 15:02:11 +0000

Passive cooling experiments from our readers. I love it!

Now all you’ve got to do is figure out a way to bring more fresh air into your basement and vent out the hot air at your roof for a poor man’s ZED home.

Reference post: http://100khouse.com/2008/01/05/zero-energy-design-binge/

By: lavardera

lavardera — Sun, 15 Jun 2008 16:10:42 +0000

I tried a passive cooling experiment yesterday using a fan and our basement. This tme of year the basement air is usually 10-15 degrees cooler than upstairs, and we dehumidify it so the air is dry as well – very comfortable down there. When you go down the steps you feel like you are stepping into a pool of cool water!

So I placed a Vornado fan – now these are not like regular house fans, they will send a directed column of air a good 20-25 feet. If you have a room without a ceiling fan one of these placed in the room pointing up will turn over the room air just as well. Anyway that fan threw a steady flow of air up the stair well and into our kitchen. The kitchen was about 5 degrees cooler than the living room space following. Both rooms have full shade, and I let it run into the evening when the sun had set. Both rooms also have cross ventilation.

By: chad

chad — Wed, 11 Jun 2008 21:26:02 +0000

Thanks Ed. I have looked into their panels but they are just too much for our budget. We are also very happy with the service from our vendor, SureTight.