What proportions of new homes are being built with balanced vs supply vs exhaust ventilation systems?
What percentages of new homes have balanced ventilation, supply ventilation or exhaust ventilation?
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Jack,
I don't have the exact numbers, but here is what I know:
- The vast majority of new homes do not have a mechanical ventilation system designed to provide fresh air to occupants.
- 大多数建筑代码都需要浴缸排气扇 - 至少对于缺乏可操作窗户的浴室。
- Many, but not all, building codes require that kitchen ranges be equipped with a range hood that has an exhaust fan ducted to the exterior.
- 曾与建筑科学公司合作的能源意识生产商中，到目前为止，最常见的机械通气系统类型是中央粉丝集成的供应通风系统。
- Many custom builders in northern New England install exhaust-only ventilation systems. A smaller percentage install balanced ventilation systems with an HRV or ERV.
- Many Canadian builders install an HRV or an ERV as standard equipment.
- Almost all Passivhaus buildings in the U.S. include an HRV or an ERV. But fewer than 100 Passivhaus buildings have been completed in the U.S.
Thanks Martin, based on your comments it sounds like perhaps 90% are a combo of intermittent de facto exhaust system(when the bathroom or kitchen fan is going) and recirculation when the heating or cooling needs to be delivered around the home.
Any idea about the level of positive pressure (Pa) from a supply ventilation system in the conditioned space vs outside it? Or how much pressure it takes to drive moisture into the walls?
I'm wondering how precisely balanced the intake & exhaust are in a balanced ventilation system, and how that shows up in any pressure differential between inside & out. It occurs to me that a "balanced system" (i.e. both supply & exhaust) with some small amount of positive pressure would tend to prevent or reduce infiltration of contaminants from an attached garage, and might even provide makeup air which could mitigate backdraft conditions - not including any 1200 cfm "Professional Chef" style range hoods, of course.
It really doesn't take pressure to drive moisture into the walls. The moisture moves from wet to dry even through drywall. Moisture movement would still happen in a perfectly air balanced house -- albeit slowly. Air leaks in the wall just REALLY speed up the problem.
非常（非常小的）略微正面的房屋是一个设计目标 - 但是对于车库而言 - 计划添加自己的通风系统 - 或者如果您要建造新房屋，则可以将其拆下。
Jack,
在设计良好的通风系统中，仅排气或供应系统的压力很小，对房屋气压的影响比风或堆栈效果较小。有关此主题的更多信息，请参阅Designing a Good Ventilation System.