Rechercher. Baisser les yeux. Et scellez d'abord les grosses fuites d'air.
De nos jours, la plupart des propriétaires comprennent qu'une maison « qui fuit » crée des problèmes de confort et impose des limites à l'efficacité énergétique. Mais quelle est la meilleure façon de résoudre le problème ?
Google "améliorations de l'efficacité énergétique" et vous êtes sûr de trouver de nombreux articles bien intentionnés vous conseillant de :
- Calfeutrez autour des fenêtres et des portes
- Remplacez les anciennes fenêtres ou ajoutez des contre-fenêtres
- Remplacer les anciennes portes extérieures
- Renforcez vos coupe-froid
- Calfeutrez autour des prises sur les murs extérieurs
- Augmentez la valeur R de votre isolation
Etc. Alors que bon nombre de ces améliorations amélioreront probablement l'efficacité énergétique et le confort à petite échelle, il ne pourrait y avoir de cas plus clair de manque de forêt pour les arbres.
Les plus grosses fuites d'air ne se situent pas autour des fenêtres et des portes.
Si vous êtes déterminé à resserrer l'enveloppe de votre maison en scellant les espaces où l'air entre et sort, tout ce que vous avez à faire est de lever les yeux. Alors regarde en bas. C'est là que se trouvent les plus grosses fuites.
Nous savons. Vous ne pouvez pas les voir. Ils ne sont pas aussi évidents que les fuites autour des fenêtres, c'est pourquoi la plupart des gens ne réalisent pas qu'ils sont là.
Voici comment les trouver :La prochaine fois que vous entrerez dans votre grenier ou votre vide sanitaire, notez toutes les pénétrations électriques, de plomberie et de conduits d'air. Dans la plupart des maisons, il y a des fils et des tuyaux à gogo ! Les ventilateurs de plafond et les éclairages encastrés sont également de gros coupables.
Lorsque les entrepreneurs ont installé cet équipement, ils ont dû percer ou percer des trous dans votre plafond ou votre plancher. Le plus souvent, ils agrandissent les trous plus qu'ils ne le devraient, permettant à beaucoup d'air de s'échapper.
Ce sont les plus grandes lacunes dans votre enveloppe de maison. Ce sont eux que vous devez sceller en premier.
In most homes, sealing these leaks saves much more on utility bills and improves comfort over and beyond what you gain from replacing your windows - even if you purchase the newfangled, foam-filled models with low-e glass! It's a little messy because you either have to lift up or temporarily remove attic or crawl space insulation. But it's well worth the trouble.
And the fact that you're eliminating the biggest leaks is only part of the story.
Before sealing leaks, understand the stack effect.
L'air chaud monte. You knew that, right?
Did you know that it also sinks? That little fact often surprises people, but it's true in some circumstances. The important thing to remember, though, is that air inside a closed system, like your home, travels up and down. We call this phenomenon the "stack effect". The biggest pressure boundaries in your home are at the top and bottom, not the sides.
Here's how it works in winter:Cold, dense air enters from below (air leaks in your crawl space) and pushes warm air upwards, through leaks in your attic.
In the summertime, things work differently. The air outside is warmer; it enters through your attic while cooler, denser air inside your home escapes through leaks in the bottom of the envelope.
What does all of this mean in the context of air sealing? Basically, the relative size of gaps at the top and bottom of the envelope isn't the only reason to seal your attic and crawl space first. The fact that more air enters and escapes from those areas anyway means they should be your top priority when pursuing energy improvements.
When it comes to home performance, here's how to proceed
To confirm whether your attic and crawl space are the biggest sources of air leakage - and they almost always are! - you should really invest in a home assessment from a Building Performance Institute-certified professional. The assessment will also reveal other major air sealing opportunities that are unique to your home.
That being said, following these steps usually results in maximum energy savings and prioritizes the most significant comfort improvements:
- Seal attic and crawl space air leaks: You're addressing the biggest pressure boundaries, and you're probably eliminating the biggest leaks at the same time.
- Increase attic insulation and encapsulate the crawl space: After you've sealed attic air leaks, it might make sense to increase the R-value of your insulation - especially if you've got old batts labeled R-19 or below. If your air handler is in your attic, consider using spray foam insulation to bring all of your indoor HVAC equipment and ductwork into the building envelope. Crawl space encapsulation does the same for your crawl space and offers other benefits as well.
- Caulking and air sealing around windows and doors: Until pretty recently, most window and door installers just stuffed fiberglass around each unit and covered it up with trim. Fiberglass isn't an air barrier, though. To properly seal around windows and doors, you need to remove the trim, yank out the fiberglass, and replace it with low-expansion spray foam.
- Caulking and air sealing other small gaps and cracks: Only worry about electrical outlets and other random wall penetrations after you've dealt with the big stuff.
Notice how "window replacement" didn't make our list? Replacing your windows is expensive and doesn't provide much ROI in terms of energy savings and comfort - at least not when you compare it to sealing your attic and crawl space. The same goes for replacing HVAC equipment. Should you replace it when it's old and worn out? Absolument. But replacing it as a "quick win" for better efficiency and comfort isn't always the best choice.
Instead, seal leaks at the top and bottom of the envelope. You'll probably be amazed at the comfort gains.