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I work for a high-end custom residential GC and have see a lot of high end HVAC systems. The new trends are as follows: HRV (heat recovery ventilators) are pr

I work for a high-end custom residential GC and have see a lot of high end HVAC systems. The new trends are as follows: HRV (heat recovery ventilators) are pretty in. Basically they are auxiliary units that source outside fresh air or exhaust stale air when there is a heat differential between a specific heating/cooling zone and the outside temps. So if you are in a basement that is cold and the outside is hot it will just bring in outside air instead of turning on the heater. Radiant floor heating and radiant cooling zones are also in. And run water through Your floors to heat or cool zones. It is one of the most efficient ways to heat a structure and feels good as well. Geothermal is also pretty in for high-end residences but there is a high first cost to evaluate geothermal potential. Most of these new technologies are usually coupled with standard split-systems or VRF systems and add additional efficiency (life cycle cost value) over the span of occupancy but have higher first costs . Lastly— always consider passive heating and cooling strategies they are highest value options (insulation , shading, glazing specs , solar orientation , landscaping , etc.)

nullc 6y ago
> So if you are in a basement that is cold and the outside is hot it will just bring in outside air instead of turning on the heater. Uh. Purpose of the HRV is to attempt to preserve the inside heat (usually both latent and sensible, using a rotating exchanger wheel) while bringing in fresh outside air. They allow you to seal the building up really good, which is good for energy efficiency, without having insufficient ventilation and getting high CO2 levels. Because they're not perfectly efficient, you can use them to move the inside temp closer to outside-- but just plain outside air exchange would do it better. :)
sh1mmer 6y ago
Curious where you are located. I was talking with our high end GC in Texas and they basically said Geothermal for heat exchange never seems to pan out for clients after the numbers are run. This seemed surprising to me. Some of the other stuff you mentioned came up, we also talked about if homogeneous household temperature was something we cared about because keeping the whole house 68 is way more intensive than having some variance in different spots of the house. Also breezeways are awesome in hot climates.
- ip26 6y ago
  The claim I have heard is, because the boreholes are such a huge portion of the cost, it comes down to the local talent base for drilling. If you live in an area full of deep rural wells and fracking, the expertise is plentiful. But if you live somewhere with no drilling activity, it will be too expensive. Horizontal loops are much simpler, but require more land area than your typical suburban plot.
- cameldrv 6y ago
  I think that geothermal works better in more extreme climates. If you compare it to an air source heat pump, the main advantage of geothermal is that the sink temperature is the ground temperature, which is roughly the average of the temperature over the course of the year. In say, Austin, TX, the difference between the average high in August and January is 35.5degF. In say, Chicago, it's 52.7degF. In Austin, the average temperature is 69degF. In Chicago, it's 52degF. The Austin average temperature is essentially room temperature, and the deviation is much less, so the total amount of heating/cooling you have to do is much less, so any efficiency advantage is reduced by the smaller need to heat/cool. This compounds with the fact that the average yearly temperature is closer to the outside air temperature, which makes the advantage of the ground source less. This compounds with the fact that Texas energy prices are some of the lowest in the country, and it makes it a lot harder to justify a big capital expense to reduce these costs.
- EricE 6y ago
  Yes, I did a lot of research into geothermal when I needed to replace a unit a few years back and there is no way I would have been able to recover the installation costs - even if I lived in the Northern most reaches of Canada instead of the mid Atlantic. Also it's very hard to find contractors skilled in installing the pipe correctly and far too many people had problems where they had to dig up portions of the loops for repairs. If I ever have the chance I will have radiant floor heating. Once you experience it you won't ever want any other kind of heat. The colder it is outside, the better it feels - it's the ultimate luxury IMNSHO.
- dhruvkar 6y ago
  I'm in the Midwest. Didn't know geothermal was a thing in most places.
rudedogg 6y ago
> Radiant floor heating and radiant cooling zones are also in. And run water through Your floors to heat or cool zones. It is one of the most efficient ways to heat a structure and feels good as well. I think/thought radiant cooling is still pretty "experimental". I think in certain climates it can cause the pipes to "sweat" a lot. If you want to see some ultra high-end stuff, you can check out this YouTube channel: https://www.youtube.com/watch?v=OrG7oG8Tvp8 https://www.youtube.com/watch?v=OrG7oG8Tvp8 Here's their video on radiant cooling (https://www.youtube.com/watch?v=rPC0_LxlwIY https://www.youtube.com/watch?v=rPC0_LxlwIY). Not sure how to word this - but my understanding is that the stuff on his channel is pretty cutting-edge. Most builders use older/time tested materials and methods. You may get weird looks if you start asking your contractor about the things you see in his videos. Also, everything is very climate specific. Mini-splits won't work if you're building a home in a very cold climate, etc. If you have the money, there are HVAC engineers that will do a way better job than a local installer. If you don't, I'd just check reviews and go with a HVAC contractor with a good reputation.
- deleted 6y ago
  [deleted]
- Schweigi 6y ago
  We used to install a lot of radiant cooling systems already back in the 90ies when I was still working as an HVAC engineer before switching to software development. Mostly for commercial buildings like banks, offices and museums. It might be too expensive in residential homes but also in Switzerland we usually don’t do a lot of active cooling for residential properties. Radiant cooling is definitely the most comfortable way to cool. In addition, it only requires small pipes for air circulation as the air is not used for the actual cooling. Thus less issues with drafts and space requirements. If I would build my own home and money isn’t tight then I would definitely go for a radiant cooling system. Thought you need to find a company with experience installing those systems. Since moving to the US I mostly see split systems. I’m not sure how many contractor here have experience with radiant coling systems.
  - kevinh456 6y ago
bofh23 6y ago
HRVs and ERVs are for fresh air ventilation in well insulated buildings. They save energy over a simple vent by transferring heat (or lack of heat) from stale conditioned exhaust air to incoming fresh air. I think ERVs also deal with moisture. A separate device called an air-side economizer can be added to a central air conditioner system. It can save energy when it’s colder and dryer outside a building than inside. When conditions are right, cold, dry outside air is pulled in and warm building air is exhausted reducing the need to run the AC compressor. Air-Side Economizer | Products | ENERGY STAR https://www.energystar.gov/products/low_carbon_it_campaign/12_ways_save_energy_data_center/air_side_economizer https://www.energystar.gov/products/low_carbon_it_campaign/1...
staticautomatic 6y ago
I once worked on a construction defect lawsuit involving a radiant system with pipes embedded in concrete, and repairs were a costly nightmare whenever anything went wrong. Is putting them in concrete uncommon?
- galfarragem 6y ago
  Embedding them in mortar (cement + sand + water)[0] is standard if not mandatory. I helped installing them in several houses and never had any problem. Relevant best practices to prevent problems by thermal dilatations in radiant floors: using the right amount of mortar aditives, using an approved isolant base for the pipes and using a foam stripe between walls and radiant floor. [0] Concrete = cement + sand + water + small rocks and often uses a grid made of structural steel.
shanecleveland 6y ago
A family member has a large home with in-floor radiant heating supplied by a boiler. There are some really nice things about it: Many individual zones, no forced-air, put your towel on the floor before getting in the shower, and have a nice warm towel when you get out :) But, all of those lines feeding different zones end up heating other zones along the way. I feel that it is often too hot in many parts of the house. The boiler is in a separate room in the basement. And that room gets very hot and ultimately the entire basement is too warm. Its a neat system, but ultimately, and for all of its promises and nice parts, it doesn't actually seem like the most effective system. I'm not sure what the answer is, but I know that I would love to have multiple, separately-controlled zones in my house. Even if the method is not the most advanced or efficient, it seems better than needlessly heating parts of a home that don't need it or overheating some parts to ensure others get warm enough.

nullc 6y ago

> So if you are in a basement that is cold and the outside is hot it will just bring in outside air instead of turning on the heater. Uh. Purpose of the HRV is to attempt to preserve the inside heat (usually both latent and sensible, using a rotating exchanger wheel) while bringing in fresh outside air. They allow you to seal the building up really good, which is good for energy efficiency, without having insufficient ventilation and getting high CO2 levels. Because they're not perfectly efficient, you can use them to move the inside temp closer to outside-- but just plain outside air exchange would do it better. :)

sh1mmer 6y ago

Curious where you are located. I was talking with our high end GC in Texas and they basically said Geothermal for heat exchange never seems to pan out for clients after the numbers are run. This seemed surprising to me. Some of the other stuff you mentioned came up, we also talked about if homogeneous household temperature was something we cared about because keeping the whole house 68 is way more intensive than having some variance in different spots of the house. Also breezeways are awesome in hot climates.

ip26 6y ago
The claim I have heard is, because the boreholes are such a huge portion of the cost, it comes down to the local talent base for drilling. If you live in an area full of deep rural wells and fracking, the expertise is plentiful. But if you live somewhere with no drilling activity, it will be too expensive. Horizontal loops are much simpler, but require more land area than your typical suburban plot.
cameldrv 6y ago
I think that geothermal works better in more extreme climates. If you compare it to an air source heat pump, the main advantage of geothermal is that the sink temperature is the ground temperature, which is roughly the average of the temperature over the course of the year. In say, Austin, TX, the difference between the average high in August and January is 35.5degF. In say, Chicago, it's 52.7degF. In Austin, the average temperature is 69degF. In Chicago, it's 52degF. The Austin average temperature is essentially room temperature, and the deviation is much less, so the total amount of heating/cooling you have to do is much less, so any efficiency advantage is reduced by the smaller need to heat/cool. This compounds with the fact that the average yearly temperature is closer to the outside air temperature, which makes the advantage of the ground source less. This compounds with the fact that Texas energy prices are some of the lowest in the country, and it makes it a lot harder to justify a big capital expense to reduce these costs.
EricE 6y ago
Yes, I did a lot of research into geothermal when I needed to replace a unit a few years back and there is no way I would have been able to recover the installation costs - even if I lived in the Northern most reaches of Canada instead of the mid Atlantic. Also it's very hard to find contractors skilled in installing the pipe correctly and far too many people had problems where they had to dig up portions of the loops for repairs. If I ever have the chance I will have radiant floor heating. Once you experience it you won't ever want any other kind of heat. The colder it is outside, the better it feels - it's the ultimate luxury IMNSHO.
dhruvkar 6y ago
I'm in the Midwest. Didn't know geothermal was a thing in most places.

rudedogg 6y ago

> Radiant floor heating and radiant cooling zones are also in. And run water through Your floors to heat or cool zones. It is one of the most efficient ways to heat a structure and feels good as well. I think/thought radiant cooling is still pretty "experimental". I think in certain climates it can cause the pipes to "sweat" a lot. If you want to see some ultra high-end stuff, you can check out this YouTube channel: https://www.youtube.com/watch?v=OrG7oG8Tvp8 https://www.youtube.com/watch?v=OrG7oG8Tvp8 Here's their video on radiant cooling (https://www.youtube.com/watch?v=rPC0_LxlwIY https://www.youtube.com/watch?v=rPC0_LxlwIY). Not sure how to word this - but my understanding is that the stuff on his channel is pretty cutting-edge. Most builders use older/time tested materials and methods. You may get weird looks if you start asking your contractor about the things you see in his videos. Also, everything is very climate specific. Mini-splits won't work if you're building a home in a very cold climate, etc. If you have the money, there are HVAC engineers that will do a way better job than a local installer. If you don't, I'd just check reviews and go with a HVAC contractor with a good reputation.

deleted 6y ago
[deleted]
Schweigi 6y ago
We used to install a lot of radiant cooling systems already back in the 90ies when I was still working as an HVAC engineer before switching to software development. Mostly for commercial buildings like banks, offices and museums. It might be too expensive in residential homes but also in Switzerland we usually don’t do a lot of active cooling for residential properties. Radiant cooling is definitely the most comfortable way to cool. In addition, it only requires small pipes for air circulation as the air is not used for the actual cooling. Thus less issues with drafts and space requirements. If I would build my own home and money isn’t tight then I would definitely go for a radiant cooling system. Thought you need to find a company with experience installing those systems. Since moving to the US I mostly see split systems. I’m not sure how many contractor here have experience with radiant coling systems.
- kevinh456 6y ago

bofh23 6y ago

HRVs and ERVs are for fresh air ventilation in well insulated buildings. They save energy over a simple vent by transferring heat (or lack of heat) from stale conditioned exhaust air to incoming fresh air. I think ERVs also deal with moisture. A separate device called an air-side economizer can be added to a central air conditioner system. It can save energy when it’s colder and dryer outside a building than inside. When conditions are right, cold, dry outside air is pulled in and warm building air is exhausted reducing the need to run the AC compressor. Air-Side Economizer | Products | ENERGY STAR https://www.energystar.gov/products/low_carbon_it_campaign/12_ways_save_energy_data_center/air_side_economizer https://www.energystar.gov/products/low_carbon_it_campaign/1...

staticautomatic 6y ago

I once worked on a construction defect lawsuit involving a radiant system with pipes embedded in concrete, and repairs were a costly nightmare whenever anything went wrong. Is putting them in concrete uncommon?

galfarragem 6y ago
Embedding them in mortar (cement + sand + water)[0] is standard if not mandatory. I helped installing them in several houses and never had any problem. Relevant best practices to prevent problems by thermal dilatations in radiant floors: using the right amount of mortar aditives, using an approved isolant base for the pipes and using a foam stripe between walls and radiant floor. [0] Concrete = cement + sand + water + small rocks and often uses a grid made of structural steel.

shanecleveland 6y ago

A family member has a large home with in-floor radiant heating supplied by a boiler. There are some really nice things about it: Many individual zones, no forced-air, put your towel on the floor before getting in the shower, and have a nice warm towel when you get out :) But, all of those lines feeding different zones end up heating other zones along the way. I feel that it is often too hot in many parts of the house. The boiler is in a separate room in the basement. And that room gets very hot and ultimately the entire basement is too warm. Its a neat system, but ultimately, and for all of its promises and nice parts, it doesn't actually seem like the most effective system. I'm not sure what the answer is, but I know that I would love to have multiple, separately-controlled zones in my house. Even if the method is not the most advanced or efficient, it seems better than needlessly heating parts of a home that don't need it or overheating some parts to ensure others get warm enough.