[ag56]

Depends so much on your climate.

Heat: the best by far is under floor heating (hot water not electric). Each room will have its own thermostat. There will be no cold spots, it will just feel cozy. No air is being cycled around the room keeping dust down.

Ventilation: indoor pollution is usually many multiples of outdoor. You want a an MVHR (or MEV) system to exchange the air in the house for fresh air with low heat (energy) loss.

AC: You need to move cold air around for this unfortunately. Pumping chilled water through your under floor heating pipes risks condensation in crawl spaces, and even if it doesn’t it simply doesn’t work very well. (Source: I had ‘radiant cooling’ ceiling panels in my last house.) I would look into a mini-duct or ductless AC system so you can control each room individually.

In climates that require heat and cooling, it is far more cost effective to go with a standard HVAC system, unfortunately, as you’ll be putting ducts throughout the house for AC. (Why put a separate system in for heating when you could just move hot air around?) But if you want the best, not cheapest, solution you really want under floor heating.

[xyzzy_plugh]

> No air is being cycled around the room keeping dust down.

I don't get this. Moving air around your home is absolutely wonderful.

Even if you have no heating or cooling going on, keeping a constant flow of air helps keep dust down by filtering it, helps even the temperature (maybe part of your home heats up in the afternoon) and most importantly keeps the CO2 levels consistent.

If I turn my HVAC fan off, any room I'm in will climb to almost 1000 ppm CO2 in hours. If I leave the fan on, every room stays well below 600 ppm.

Flipping the fan switch from "auto" to "on" on my thermostat has been one of the best quality of life improvements ever.

[tempestn]

Your parent mentions installing an MEV, which would provide the same benefit of keeping CO2 down. Of course, it also moves air around.

I agree with you though that anyone with a central HVAC system should consider leaving the fan in 'On' mode. Also occasionally opening a window and/or running bathroom exhaust fans will allow the hvac system to pull in more outside air. Normally they have a fresh air inlet, but if the house is sealed up well, it will have positive pressure, so little external air will be pulled in. An HEV will do this more efficiently, but if you live in a moderate climate, simply using a window or exhaust fan along with the hvac fan is probably sufficient.

[bleepblorp]

Underfloor has to be done right (installed on materials with a very low thermal mass) or it will be horrible in buildings that have a highly variable heating load.

Underfloor systems applied directly to concrete subfloors will take many hours to change temperature. In climates with a large spread between daytime and nighttime temperatures, such underfloor heating systems will either overheat the building during the day or be unable to ramp up quickly enough to heat at night.

Also be aware that underfloor heating systems are only compatible with a subset of flooring materials and don't like area rugs.

[ubertoop]

> Ventilation: indoor pollution is usually many multiples of outdoor. You want a an MVHR (or MEV) system to exchange the air in the house for fresh air with low heat (energy) loss.

Can you expand on this? What is polluting the indoors? How can I verify it's true at my home?

[danielheath]

Your body constantly sheds skin flakes (dust).

Tiny mites find those flakes, cover them in enzymes that break down skin, then wait for them to break down enough to eat.

When a puff of air lifts the dust into your lungs, those digestive enzymes attack your lungs.

Your body produces extra mucus in response, to trap dust on the way in, and inflames the tissue surrounding any damage to prevent infection taking hold. Neither response is pleasant.

[EricE]

And if you think that's bad, just do an air sample after running a vacuum. Micron filters or not. It's one of the many reasons I love my central vacuum system - it exhausts outside my home :)

[clairity]

anything not N₂, O₂, argon, or H₂O is possibly air pollution, though some things are more harmful than others. many mundane things indoors give off VOCs (volatile organic compounds), from couch cushions to stained/painted woodwork. carbon dioxide, carbon monoxide, and ozone are air pollutants too. then you've got particulates like soot, smog, dust, pet dander, fly ash, dust mites, mold spores, pollen, etc. and then anything that smells from candles, perfumes, and soaps to smoke from cooking is more pollution. and that's just the stuff in the air (much more of a risk to humans than airborne viruses btw).

[bleepblorp]

Indoor air pollution is mostly carbon dioxide, combustion byproducts (in houses with propane/gas cooking appliances), volatile organic compounds that offgas from plastics, paints, rubbers, and similar materials, and assorted particulate matter.

[tempestn]

To answer the second half of your question, you can pick up one of these to measure CO2 level (1). Some specific things to check would be the kitchen while cooking, or the bedroom overnight.

If you live in a moderate climate, rather than an HEV, you can likely get away with just running bathroom exhaust fans for a portion of the day; you can get switches that will do this automatically.

1: https://www.amazon.com/Hydrofarm-Autopilot-Desktop-Monitor-L...

[xyzzy_plugh]

Cooking in the kitchen is one of the worst offenders for air quality, for example.

[pcdoodle]

Smoking cigs beats it on a PM 25 and PM 10 readings.

[ubertoop]

... how are you supposed to not cook in your kitchen?

I suppose I should just eat all my food delivery now?

[mariushn]

> Heat: the best by far is under floor heating (hot water not electric).

Why water? My neighbour has electric and it works great (besides higher cost). No danger of broken pipes, no central unit to heat & move the water.

[EricE]

Electric is crazy expensive to just about anything else unless you live in an area subsidized by cheap hydro power.

Loops in new construction are out of synthetic pipes that are one continuous piece - no joints other than at the manifolds. Most systems have the pipes installed in concrete (yes, there is lightweight concrete for floors with wood joists; I've considered it) so unless you are deliberately stupid you aren't going to puncture the piping. Water in the system also counts towards the systems overall thermal mass to, helping keep the heat consistent.

Since few people seem to experience radiant heat it's pretty hard to state just how different it is and feels. It's amazingly comfortable.

[pcdoodle]

Doesn't want to turn the whole house into a 60hz panel antenna possibly?