Mechanical vs. Natural Ventilation
goodomens
| Posted in General Questions on
Ventilate right V Crack the windows
30×32 open concept + loft
3.5/12 single pitch
9′ walkout basement
Hearthstone 40 in kitchen NE 1st floor
Possible custom masonry heater 8×4 (footed) could sub for hearthstone Mansfield or pellet stove
Built tight. Considering 3 sets of lunos, but comparing it to open windows. Not gonna do ductwork.
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Replies
goodomens,
Does your code not require mechanical ventilation?
The problem with relying on the windows is twofold:
- You never know how much air is coming in so you end up either under or over-ventilating.
- There is an energy penalty.
Lunos, or other spot ventilation isn't the only non-ducted alternative to windows. You can also use either a supply or exhaust only system. The simplest is to just run a bathroom exhaust fan continuously.
Do you plan on integrating outside combustion air for the pellet stove and masonry heater? You said "built tight" so there will be some issues with these devices unless you plan now for them.
I have 2 issues with Lunos and similar systems: 1. Filtration to levels around MERV13 is pretty impossible. 2. Sound transmission. If you live near a busy street etc., they are essentially straight pipes to the outside.
I'm assuming this home will have no ducting at all correct? Will it have AC?
I have a strong feeling that in 10-15 years we're going to look back at today's arguments against balanced ventilation the way we look back now at the days of no insulation, open fireplaces and horse-drawn carriages: a reminder of simpler times when we didn't know better. New, tight homes should have balanced ventilation systems.
If it's too late for ducts, you could go with the Panasonic unit: https://www.supplyhouse.com/Panasonic-FV-04VE1-WhisperComfort-40-20-or-20-10-CFM-Ceiling-Spot-Energy-Recovery-Ventilator
It's half the cost of the Lunos I think? 40cfm, only needs the duct to the outside so depending on location that run can be pretty short.
Andy, the small Panasonic is quite inefficient for cold climates, so would not be recommended depending on the OP's climate zone. I've tested one in the 55-60 % range of efficiency around ambient freezing conditions. It's good for 35 CFM on supply, max.
Ah, good to know. I've seen them used around here in the mellower end of Zone 4 to solve ventilation issues for smaller spaces or to avoid long duct runs.
Andy, agreed, Zone 4 would be a better case for the Panasonic spot ERV.
I live in a 120 year old stone house (huge thermal mass) in a temperate marine zone (in France). The windows are open pretty much all the time for about 8 months of the year. For 2 of those months I have heating in the bedrooms, and for the other 4 we heat parts of the house we use regularly.
I'm a big advocate of opening windows.
It's all about climate zones.
Much of the information on this site focuses on cold northern climates and is VERY useful in those regions. But for those of us living in more moderate climates it's important to keep that in mind and make appropriate adjustments.
And just so there's no misunderstanding, this site is great for people living in all climate zones. Just remember to keep in mind the differences.
It's always a case of adjusting to meet the needs of your specific climate, but the reason there is so much discussion here about the needs of cold northern climates is that they take a fair amount of resources to keep comfortable.
When I lived right by the beach in Southern California I didn't have a heating or cooling bill. I think we had a heater in the house but I don't think we even knew how to turn it on as we never needed to in the few years I lived there. Contrast that to my previous house in Vermont where heating oil and firewood were huge expenses for us ski bums. If it wasn't a rental I would have been trying every which way to improve the Vermont house but in SoCal it didn't even cross my mind.
It is rare to live in such a nice location where opening windows often does not lead to other unintended consequences like humidity, pollen/allergens, pollutants/IAQ issues, bugs/critters, etc. Consider yourself lucky!
I was lucky to live there when I did, but now I'm up in the Pacific Northwest where heating bills are once again a reality and with climate change we might soon need air conditioning too!
There was one occasional downside I remember from my time there...wave noise at night! Rough surf could be sometimes be loud enough that you'd have to shut the windows to sleep.