Building Science - Building a super efficient home

In that regard I will challenge your last point as it is not exclusive to ducted systems. The Mitsu Mr. Slim I was looking at can heat down to -25C.

You still need backup heat. I would never advise a customer to rely solely on a ductless mini-split for heating in our climate.

If something goes wrong (and during defrost cycles), you need to have another source of heat!
 
Here are the pros that lead me to change from considering central air to ductless.

1) Ease of installation ->Cost. It's really simple to install, even more so on a new construction so for the same money you can get better equipment instead of paying for Joe Blo to be installing ducts
2) Efficiency. Ducts, even insulated will loss heat or cold air, some say up to 20%
3) Space. A unit outside and a few units up on the wall inside. No bulky mechanical systems in the basement. Smaller house possible or more living space in same footprint
4) Sound. Ducts don't always but can carry sound thru the house. Ductless doesn't and a good unit is whisper quiet

The cons.

a) Big house. If you have >2500sqft or you have a lot of twist and turns the air from a head unit might not get around like central
b) Things on the wall. Not everybody likes bricks hanging from the wall. There are hidden ductless alternatives but you sacrifice performance
c) Not as flexible. There are so many "attachments" you can build into the central air. Ductless is whatever the unit has and because you can only have it be so big a full central system can be made much better (at a cost).

Personally the cons don't really apply for my intended build so the pros won me over

1. You can get better equipment, but will it *work* better to provide overall comfort? Maybe it will, in that case, go for it!

2. Ducts do have losses. However, if they are in conditionned space, it’s really not that bad. If they run in attics or unconditionned basements, insulation is a big factor and a poorly built setup can sure be a problem.

3. Can’t argue with that!

4. A ductless unit running full speed is not so quiet. Running at reduced speed, sure, just like a ducted system. ;-) I can hardly hear mine most of the time.

A) true

B) true

C) also true
 
Foyé de masse c cool aussi, avec des passes d'eau dedans tu chauffes toutes la maison pour des peanuts...
 
What's wrong with baseboard heaters?

It doesn't use any fancy physics principles but the cost is so much lower that at the end of 15-20 years it must be about the same no?
 
You still need backup heat. I would never advise a customer to rely solely on a ductless mini-split for heating in our climate.

If something goes wrong (and during defrost cycles), you need to have another source of heat!

Back up I had in mind was a design that would lose no more than 2-3 degrees per 24 hours with zero power @-30C. Even starting at 18 degrees that's a good 3 days before it starts to get bad with no power, no solar gain, no human heat, no cooking heat, no electronics heat. In a typical setting 10 minutes of defrost every half hour will not even be noticed.

What's wrong with baseboard heaters?

It doesn't use any fancy physics principles but the cost is so much lower that at the end of 15-20 years it must be about the same no?

Nothing really but efficiency wise they are not so great. Pumps get 2-3W of heating for every watt of electricity used, resistive heaters are 1 to 1.
 
Back up I had in mind was a design that would lose no more than 2-3 degrees per 24 hours with zero power @-30C. Even starting at 18 degrees that's a good 3 days before it starts to get bad with no power, no solar gain, no human heat, no cooking heat, no electronics heat. In a typical setting 10 minutes of defrost every half hour will not even be noticed.

I guess if you could achieve that you would be fine without backup.
 
Foyé de masse c cool aussi, avec des passes d'eau dedans tu chauffes toutes la maison pour des peanuts...

Même sans tuyauterie, si la maison est bâtie autour, ça le fait. Par contre, pas vraiment le choix d'avoir une prise d'air extérieur et des portes isolées et bien scellées si tu veux pas "perdre de l'air" par là tout en ayant un bon apport d'air, surtout dans le contexte d'une maison très efficace.
 
Foyé de masse c cool aussi, avec des passes d'eau dedans tu chauffes toutes la maison pour des peanuts...

c'Est cool et une super belle chaleur (Un chum s'en ai fait faire un y a un couple d'année pour remplacer son combustion lente).
Mais tu dois encore géré du bois (cordé, déplacé), parti le foyer 1-2-3 fois par jour.
ET ca coute une estifi de beurré versus un bon combustion lente, si c'Est juste pour le "fun" et de chauffé un peu.

Le bois doit vraiment etre ton chauffage #1 pour se payer un foyer de masse.
 
And you can set different rooms at different temperature. In central system, the house is always at the same temperature. You cannot change the main floor temperature during the night. I guess you could add dampers to different rooms and control them with independent thermostats too...

Mr Slim and such seems to accommodate 6+ wall unit. But such systems seems appropriate for small to medium house and not so nice for big houses. There will be more temperature difference in larger room. And as @cur@ pointed out, you also need a backup system. Central heat system use electric elements.

One thing I was wondering is the water heater. I wonder why they cannot be connected with the condenser. In summer you could inject the heat cooling the house in the hot water; in winter you would run your more efficient heat pump to heat the water.

Also, you can collect the energy from the shower drain to heat the cold water getting in the water tank. but again, payback is very long.
http://www.ecohabitation.com/certification/renovation/salle-bain/recuperateur-chaleur-eaux-grises
 
Also, you can collect the energy from the shower drain to heat the cold water getting in the water tank. but again, payback is very long.
http://www.ecohabitation.com/certification/renovation/salle-bain/recuperateur-chaleur-eaux-grises

Yeah, they are nice systems in theory but I have doubt about how actually efficient they are in real life applications. Also, with all appliances using less and less water, these system become less and less useful. This is mostly true in a single house, I can see them work wonders in larger applications. Actually LEED certification give points for their usage.

Think of taking a bath, using a washing machine or a dishwasher, by the time you actually reject the hot water, your hot water tank might have already refilled itself with cold water. In a multiplex or commercial application, the stream of hot piss is more constant... makes more sense then.

The coil system ( Ecodrain), is close to 1000$ once installed. I feel like there is a lot of better places to invest that money when talking about a single home. You DIY make one though if you are ready to deal with that...

Edit: Reno-Depot sells them

https://www.homedepot.ca/en/home/p.1000698154.html?eid=PS_GOOGLE_HD+%7C+PLAs_Shopping+%7C+Building+Materials_Building+Materials_pla-308729290475&gclid=CjwKCAiAweXTBRAhEiwAmb3Xu0KiWYx1TpNQE39EEnoZLNQBUQCY9X1TFFxT52Jbra9M_jYGwEbOqhoCwxUQAvD_BwE
 
One thing I was wondering is the water heater. I wonder why they cannot be connected with the condenser. In summer you could inject the heat cooling the house in the hot water; in winter you would run your more efficient heat pump to heat the water.

Also, you can collect the energy from the shower drain to heat the cold water getting in the water tank. but again, payback is very long.
http://www.ecohabitation.com/certification/renovation/salle-bain/recuperateur-chaleur-eaux-grises

Look up Rheem hybrid water pumps. It's on my wish list. If the bill is not already too high it's definitely something I plan to install.

About the drain, Ronin is right, nice but diminishing returns. Youre better off to adjust habits, i.e. take shorter shower. Free upgrade but not sure how "compatible" it is with the wife. A good low flow shower head is another better bang for the buck.
 
Posting just to vent off as I'm currently in the process of spending hard earned money on :
Furnace heating element (Qty 1 : 300$)
Contactor on Thermopump (Qty 1 : 130$)
Diagnostic of Air exchanger (from the 19th century, will most likely end up scrapping and replacing it)
and labor (@ 80$/hr)
Fuuuuuu.....
 
Posting just to vent off as I'm currently in the process of spending hard earned money on :
Furnace heating element (Qty 1 : 300$)
Contactor on Thermopump (Qty 1 : 130$)
Diagnostic of Air exchanger (from the 19th century, will most likely end up scrapping and replacing it)
and labor (@ 80$/hr)
Fuuuuuu.....

Hence why, among other things, to me HVAC system are cancer in small residential houses. You gotta design in order to minimize their requirements. They are money pit waiting to suck you in.
 
And you can set different rooms at different temperature. In central system, the house is always at the same temperature. You cannot change the main floor temperature during the night. I guess you could add dampers to different rooms and control them with independent thermostats too...

Mr Slim and such seems to accommodate 6+ wall unit. But such systems seems appropriate for small to medium house and not so nice for big houses. There will be more temperature difference in larger room. And as @cur@ pointed out, you also need a backup system. Central heat system use electric elements.

Central systems can totally be zoned and you can change the temperature at night!

You can use «smart*» thermostats, controllers, sensors, etc. The options are endless.

A multi-split system with that many indoor units will be very expensive, and then you got several units hanging on the walls, several filters to clean in different rooms, etc.
 
Look up Rheem hybrid water pumps. It's on my wish list. If the bill is not already too high it's definitely something I plan to install.
About the drain, Ronin is right, nice but diminishing returns. Youre better off to adjust habits, i.e. take shorter shower. Free upgrade but not sure how "compatible" it is with the wife. A good low flow shower head is another better bang for the buck.
The water heater (and recovery system) will payback if you use a lot of hot water. But the gains from one will offset the benefit of the other: If you recover more energy from the drain, any electric heater will use less energy; increasing the payback time. I looked for fun, the water heater is 1200$USD; but uses 1/3 of the energy. I would definitely look into my consumption before purchasing something like that. You can put an amp meter with a data logger on your actual water tank and see how much power you are using. If I had to choose one of the too, I would most likely look for the recovery system as the water heater has a life of +-10years. There are also fiberglass water heaters with lifetime warranty (on core).
But for the payback, I would set myself rules for maximum payback time; and do (or don’t) based on that rules and pay premium (or not). For some, paying 3k$ more for a diesel car is worth it on the long run on fuel savings. However, if you use your car 5 000km/yr; it will never payback or take 100 years.
One more thing: I like humidity controlled exhaust fan for the bathroom. You can activate the fan by touching the switch when going to the shitter.

Central systems can totally be zoned and you can change the temperature at night!
You can use «smart*» thermostats, controllers, sensors, etc. The options are endless.
A multi-split system with that many indoor units will be very expensive, and then you got several units hanging on the walls, several filters to clean in different rooms, etc.
I feel these systems are filled with compromised. After some digging, I found “Smart vent” rather than using mechanical dampers. Only problem is that it is battery powered. I am also curious to see how it will age, reliability and spare parts in 5-10 years...
https://keenhome.io/collections
 
Pour moi le.probleme des central c'est que les gens cheap out et ont justement pas ces belles zones et contrôle individuel.

Sur mes baseboard, je contrôle avec des changements plusieurs fois par jour, chaque pièce individuelle... Par exemple mon vestibule est chauffé seulement une demi heure le matin, le reste il est à 14 degrés. Le.sous sol juste le soir en semaine...

Gérer ça se fait avec un HvaC mais tu dois payer un sacré bon système pour diviser chaque pièce avec thermostat et contrôle individuel.

Au chalet on met plancher chauffant mais baseboard dans chaque piece, on a déjà eu radiant seulement et c'était de la marde, incontrollable quand tu as rien d'autre.

Sent from my Pixel 2 XL using Tapatalk
 
I feel these systems are filled with compromised. After some digging, I found “Smart vent” rather than using mechanical dampers. Only problem is that it is battery powered. I am also curious to see how it will age, reliability and spare parts in 5-10 years...
https://keenhome.io/collections

Y'auras simplement autant de compromis que la personne voudra en faire, sinon tout est possible.

Pour moi le.probleme des central c'est que les gens cheap out et ont justement pas ces belles zones et contrôle individuel.

Sur mes baseboard, je contrôle avec des changements plusieurs fois par jour, chaque pièce individuelle... Par exemple mon vestibule est chauffé seulement une demi heure le matin, le reste il est à 14 degrés. Le.sous sol juste le soir en semaine...

Gérer ça se fait avec un HvaC mais tu dois payer un sacré bon système pour diviser chaque pièce avec thermostat et contrôle individuel.

Au chalet on met plancher chauffant mais baseboard dans chaque piece, on a déjà eu radiant seulement et c'était de la marde, incontrollable quand tu as rien d'autre.

Sent from my Pixel 2 XL using Tapatalk

Tu peux faire la même chose avec un système central, mais oui ça va être plus cher. Mais je me questionne sur l'utilité de zoner CHAQUE pièce comme ça... Un moment donner, j'veux pas me promener dans ma maison pis que la température soit toute écartée! Pour quelqu'un qui a vraiment un horaire/routine fixe qui change jamais, peut-être, mais même là, j'pas sûr que la faible économie vaut la chandelle.

Puis la, on parle de chauffage, mais faut pas oublier que tu climatiseras pas grand chose avec tes calorifères. :p Qui plus est, quand t'as une thermopompe centrale, tu peux te permettre de chauffer des pièces que peut-être tu diminuerais avec tes calorifères, puisque tu consommes beaucoup moins de courant (1.5 @ 3w pour 1w, versus 1 pour 1 avec l'électrique.)

J'ai eu les deux. Murale combinée avec calorifères sur tstats programmables à plusieurs heures du jour, versus système central maintenant, et j'peux te dire que je reviendrais pas en arrière !

Cela dit, chacun est libre d'y aller à sa manière. ;)
 
Y'auras simplement autant de compromis que la personne voudra en faire, sinon tout est possible.



Tu peux faire la même chose avec un système central, mais oui ça va être plus cher. Mais je me questionne sur l'utilité de zoner CHAQUE pièce comme ça... Un moment donner, j'veux pas me promener dans ma maison pis que la température soit toute écartée! Pour quelqu'un qui a vraiment un horaire/routine fixe qui change jamais, peut-être, mais même là, j'pas sûr que la faible économie vaut la chandelle.

Puis la, on parle de chauffage, mais faut pas oublier que tu climatiseras pas grand chose avec tes calorifères. Qui plus est, quand t'as une thermopompe centrale, tu peux te permettre de chauffer des pièces que peut-être tu diminuerais avec tes calorifères, puisque tu consommes beaucoup moins de courant (1.5 @ 3w pour 1w, versus 1 pour 1 avec l'électrique.)

J'ai eu les deux. Murale combinée avec calorifères sur tstats programmables à plusieurs heures du jour, versus système central maintenant, et j'peux te dire que je reviendrais pas en arrière !

Cela dit, chacun est libre d'y aller à sa manière. ;)
Oui tu as 100% raison sur toute la ligne. Je n'ai pas d'air climatisé donc dans mon cas ça s'applique pas. L'autre chose que j'aime Des baseboards et du radiant c'est que ça fait pas de bruit du tout, veut veut pas des ducts ça fait un bruit significatif.

Si je me construisait je mettrais des ducts pour l'A/C, mais à mon avis radiant + baseboard pour chauffer est mieux en hiver.

Sent from my Pixel 2 XL using Tapatalk
 
Central systems can totally be zoned and you can change the temperature at night!

You can use «smart*» thermostats, controllers, sensors, etc. The options are endless.

A multi-split system with that many indoor units will be very expensive, and then you got several units hanging on the walls, several filters to clean in different rooms, etc.

Do you know of any systems that are capable of monitoring air quality CO2 and PM2.5 which turn the system on and off accordingly. The whole point of having these systems is to keep quality air conditions inside but if you set it up in dumb mode (example operate for 10 minutes every hour) if you go away for the weekend the air will be replaced when there would otherwise be no need to. In very hot summer days or very cold winter nights that's efficiency being piped out because of "dumb" controllers.
 
Oui tu as 100% raison sur toute la ligne. Je n'ai pas d'air climatisé donc dans mon cas ça s'applique pas. L'autre chose que j'aime Des baseboards et du radiant c'est que ça fait pas de bruit du tout, veut veut pas des ducts ça fait un bruit significatif.

Si je me construisait je mettrais des ducts pour l'A/C, mais à mon avis radiant + baseboard pour chauffer est mieux en hiver.

Sent from my Pixel 2 XL using Tapatalk

Des ducts biens conçus ne font pas beaucoup de bruit. C'est sûr que des plinthes ça fait aucun bruit donc c'est dur à battre sur cet aspect. Mais sérieusement quand ma fournaise marche à basse vitesse j'entends pratiquement rien. À haute vitesse oui je l'entends, c'est pas mal inévitable, surtout sur les runs de duct plus courtes, mais c'est vraiment pas dérangeant. Pas plus par exemple qu'une thermopompe murale ou quelque chose du genre. Pis encore mes ducts sont pas parfaits... J'ai pas eu le temps de m'en occuper comme il faut lors de la construction parce que j'étais trop débordé et maintenant ça me tente pas de défaire mon plafond suspendu partout pour apporter les modifications que je voudrais pour le rendre encore mieux...

Les gens se basent souvent sur leurs expériences avec des systèmes mal conçus (très répandus, surtout les plus vieilles maisons.) alors c'est pas toujours représentatif.

La circulation d'air accrue d'un système à air pulsé rend l'environnement beaucoup plus agréable IMO. Sans parler du contrôle de l'humidité!
 
Back
Top