Hi, I have a 2150 sq. ft. 2 story with basement (additional 950 sq ft) with 2" polished concrete floors. My home is radiantly heated through the floors with a hydronic heating system in all three floors. Water is heated with a boiler. I have a HRV system to exchange air and provide humidity control in the winter. I live in Edmonton, AB, Canada. My home is well insulated (~R28 in walls, R70 in the attic, all triple glazing/double low-E coated windows, ICF foundation/basement walls) and well sealed. The problem is that on warm sunny days, the house picks up quite a bit of heat through our many east/south/west windows. This is great in the winter but uncomfortable in the summer. Is there an economic and realistic way to cool the floors? Would it have a great impact on the internal temp of my home? If feasible, what are some of my options and approx costs involved? If not realistic, what other options might I have? I have read quite a bit on some of the problems of radiant cooling such as condensation issues. However, the climate is quite dry here even in the summer and we don't require huge cooling. I'd be happy drop my internal temp by 3-4 degrees C. Cool floors don't bother me. Excessive heat does. Thanks, Steve

You can add an air to water heat pump and pump cool water through the coils. Probably not necessary in your case (reversing solar gains), but you can extend the amount of cooling it can provide before dew point is an issue by adding dehumidification to your HRV air.

1. Roof overhangs on the South and pull-down exterior sun shades on the East and West. That is essentially a no-energy solution that will still allow you to benefit in the Winter.

Yes, if you had used a reversible heat pump in lieu of the boiler, you could operate it in chiller mode. If you have well water or a nearby stream, there are other options too.  You do need to be wary of condensation and monitor/address dew point with controller to avoid creating other problems as you indicated. A proper roof overhang design like ICF suggested should have also been used and would have greatly mitigated this overheating issue.

Humidity is the principal source of discomfort in warm weather. De-humification is the answer. You can do it will a condensing coil, floor or ceiling. I recommend the coil.

Yes you can use and coil and radiant cooling, but it is not practical in residential applications.

He's not humid.

I second ICF's statement to look at sunblocking first. but if that's not feasible, a chiller can be added or Air source heat pump which might help your heating bill, depending on your local energy costs, as you could use it in heating mode for some portion of your heating hours... depending on your final heat loads. Great specs but lots of glass... what does your winter heating bill look like currently, and using what kind of fuel?

He's not?

http://weatherspark.com/averages/28127/Edmonton-Alberta-Canada

touche!

Yes you can use and coil and radiant cooling, but it is not practical in residential applications.

Alone I agree (most climates), although when combined with dehumidification of air delivered by ERV ducts, I think it's an open question.

I would be interested in an integrated ERV with water coils. VanEE had one but not practical nor popular.

where is this "not practical" coming from? It's not that complicated or expensive. as long as you have a chilled water source planned, and a tight home.

For maximum efficiency, you would have to have a heat pump producing moderately cool water for the hydronic floor radiators and quite cool water or refrigerant for a dehumidifying air coil. Clearly doable, but what's the best way?

currently I think the best 2 strategies are tekmar 406 with dew point mixing capabilities or two separate tanks, one kept colder and one kept warmer, with priority on the smaller load (dehumidification). I'm in the process of figuring out whether the 2nd tank is cost effective but with the EER improvements of warmer water, and the relative size of the loads (very small dehumid, much larger space cooling) I suspect the two tank strategy will actually end up being a winner. though having dew point control is really, really, really nice for this app, which makes the 406 attractive even if you don't strictly need it for mixing. I'm not aware of any other residential dew point calculating aquastats or the like.

I tend to agree. Two buffer tanks that are two zones on a heat pump, one maintained at cold and the other at cool. Then some ERV duct fan coil unit that uses the cold water for dehumidification (and some cooling ). Something to add heat back to the system (ie, you want dehumidification with no cooling) might be a bonus add.

Posted By NRT.Rob on 13 May 2013 12:48 PM
where is this "not practical" coming from? It's not that complicated or expensive. as long as you have a chilled water source planned, and a tight home.

Labor.

Chilled water coil. Two adapters. Pump Takeoff. Dehumidistat. Drain. All in the mech room but the dehumidistat.

vs... what? imperfect humidity control in a cooling emitter? wasteful dedicated dehumidifiers, or as I like to call them, "Air conditioners that don't cool"?

the biggest concern for me is enclosure tightness. leaks will kill this strategy.

Enclosure tightness indeed!

Before considering a home for radiant cooling, be it floors, walls or ceiling (preferred) we perform a blower door test.

Posted By BadgerBoilerMN on 13 May 2013 12:09 PM
He's not?

http://weatherspark.com/averages/28127/Edmonton-Alberta-Canada

Not sure where weatherspark gets its info but I can tell you its out to lunch for both Calgary and Edmonton. Born and raised in southern Ontario so I know humidity. Been in Alberta for forty years and doubt if I've lost one nights sleep to humidity or high temps. Air conditioner salesmen starve out here!

Agreed, it's not humid there - look at dew points, not %RH.

Back too cooling - I agree - a tight house and room by room ERV balancing (ie, don't allow any room to be negative pressure wrt outside) and latent load should be very low. A well insulated house will insure that floor (or ceiling) temps don't need to go very low. If you already have a heat pump and ERV, then it doesn't take much more to get radiant cooling + ERV ducted cooling/dehumidification (DOAS).

Posted By jonr on 13 May 2013 05:16 PM
Agreed, it's not humid there - look at dew points, not %RH.

Back too cooling - I agree - a tight house and room by room ERV balancing (ie, don't allow any room to be negative pressure wrt outside) and latent load should be very low. If you already have a heat pump, then it doesn't take much more to get radiant + ERV ducted cooling/dehumidification (DOAS).

Exactly!  Hitting north of 80% relative humidity in August when the binned hourly average temp is ~62F isn't exactly sticky!  The dashboard view with a dew-point graph with the temperature overlay option is more useful. The RH is meaningless without the temperature to which it is relative.