答复

1. GBA编辑
   马丁·霍拉迪（Martin Holladay）|Jul 10, 2017 08:22am|＃1

   德克萨斯游骑兵，
   Q. "Would closed-cell foam on the underside of the roof decking + sealing the current ventilation pathways significantly reduce my utility costs?"

   答：是的。有关此问题的更多信息，请参见这两篇文章：

   Keeping Ducts Indoors。

   Creating a Conditioned Attic。

   问：“由于现在它们进入阁楼，我还必须将浴室通风口延伸到屋顶上。”

   答：无论您是否决定在屋顶护套的底面安装喷雾泡沫，都应该这样做。将浴室风扇发泄到阁楼上是违规的。

2. 
   anon3|2017年7月10日上午09:11|＃2

   坏主意，改用太阳能电池板。

3. 
   Stephen Sheehy|Jul 10, 2017 02:25pm|＃3

   马丁：您的回答表明是浴室风扇进入阁楼。但是他提到“浴室通风口”。我认为这意味着管道排气堆栈。无论哪种方式，他们都不应该发泄阁楼，两者都是违规行为。

4. 专家成员
   达娜·多塞特（Dana Dorsett）|2017年7月10日下午2:53|＃4

   What he said- venting a bath fan into an attic is a code violation almost everywhere, and should be corrected no matter what happens with the insulation scheme.

   每个英寸的闭孔泡沫都使用与4英寸开放式电池泡沫一样多的聚合物，因此，开放式电池的8-9“将是仅几英寸的闭合电池的聚合物。大多数闭合细胞泡沫也被吹入高环境影响HFC245FA的情况下，而所有开放的细胞泡沫都被低冲击水吹动。开放单元可以安全地完成的分数越大，它对环境（和皮夹）越好。

   在美国2＆3的美国气候区（覆盖了East TX），您只需要在屋顶甲板的底面上的闭孔泡沫即可保护屋顶甲板本身，而IRC的R806.5：

   https://up.codes/viewer/utah/int_residential_code_2015/chapter/8/ford-ceiling-construction#r806.5

   其他R33将其提高到R38，可以用（更绿）开放的细胞泡沫，成本为2/3。

   https://up.codes/viewer/general/int_residential_code_2015/chapter/11/re-energy-energy-efficicy#n1102.1.2

   To do R38 all with closed cell takes 6" of foam (in my neighborhood that would run about $6 per square foot.) To do HFC blown closed cell safely and at high quality would require three lifts of no more than 2" per pass, with a cooling period between lifts to avoid a fire risk from heat build as it cures over a few hours.

   Do do it with an inch of closed cell on the roof deck followed by 8-9" of open cell foam would be less than $4 per square foot. Some open cell foam can be safely installed in 9" lifts, but any would be good for at least 6" per pass safely.

   太阳能电池板将大约25 - 35美元每平方foot (sometimes lower in some parts of TX), but may be a better investment if your electric rates are high and you can be net-metered at retail for 20 years. The shading of the roof provides some direct reduction in cooling load, but the real benefit is the amount of power being offset over the lifecycle. But it's a MUCH bigger investment decision, even if only 1/3 the roof area.

   Whether the roof decks is insulated or not, in your climate a vented attic usually increases the moisture content of the wood inside the attic than an unvented attic. Sealing up the venting without insulating at the roof deck will increase the peak attic temperatures by several degrees, but may lower the actual cooling load by reducing infiltration and the accompanying high latent loads.

   如果有空间，当电热水器要替换时，热泵热水器将在热门阁楼中击败其额定效率。它们往往比典型的电罐高，因此可能不合适。但是，无论屋顶甲板是否是绝缘的，热泵热水器都会同时提供阁楼空间的冷却和除湿，这一切都对。