答复

1. GBA Editor
   Brian Pontolilo|2020年1月2日02:30 pm|＃1

   Hi StefanKe.

   优先提高能源的优先级可能具有挑战性。当我有一个需要大量类似工作的房屋时，我总是做预算和技能允许的下一件事，但是安装PV绝不可能是可能的，所以这是不可能的。

   In that way, what jumps out at me on your list is to air seal the attic floors. I'd try to save the blown in fiberglass and add more insulation, if you can shuffle it around while you do the air sealing work.

   I think you'd need someone to do some energy modeling to tell you if and when it made sense to add the PV system vs. some of the other potential projects.

2. Expert Member
   Zephyr7|2020年1月2日02:44 pm|＃2

   I’ll second what Brian said about air sealing the attic floor as your next project. There are a lot of potential gains from doing that.

   If you’re thinking of using #4 to create an unvented roof, don’t. Cut and cobble is not a good idea with unvented roofs since you can’t trust it to stay sealed.

   如果您从80加仑的热水器到50，您可能会注意到用完热水的变化。这可能是要考虑的事情。

   太阳能项目可能是您列表中最高的成本项目。您还可能会遇到支持系统的结构性问题（令人惊讶的成本）。

   我也会看其他空气密封工作。RIM托梁密封项目通常不太昂贵，真的可以帮助收紧房屋。爬网空间封装项目和绝缘爬网空间和/或地下室墙壁是另一个潜在节能项目。所有的空气密封和绝缘项目也倾向于改善舒适性，因此除了提高能源效率之外，它们还具有额外的好处。

   Bill

3. Expert Member
   达娜·多塞特（Dana Dorsett）|1月2日，2020年06:27 pm|＃3

   >"Spray foam roof deck in both attics with 5.5″ open cell. That’s only R18 but the contractor insists on the added air sealing capabilities when I asked for R30 ( ~8 ” of open cell). Concerns are roof leaks, thermal bridging of rafters
   Remove old insulation on attic floor"

   ------------------
   >“。固定的泡沫板夹在屋顶after子之间，用喷雾泡沫罐密封，然后通过绑带固定在适当的after子上的另一层泡沫板。
   密封山墙通风口。
   Remove old insulation on attic floor"

   That would likely increase energy use, if the ducts and attic floor are reasonably air tight.

   如果隔热屋顶甲板只有R18 do NOT remove the insulation at the attic floor, except where needed at the roof edges to create the near-perfect air seal.

   正如其他人所指出的那样，切入的泡沫泡沫是有风险的，而且耗时。热桥after架也抢走了它的潜力 - 将高r/英寸昂贵（环境和财务上）泡沫放在after绕after边缘以下的连续层中，然后将after架留空了要好得多。算一算：

   https://www.finehomebuilding.com/2017/07/10/closed-cell-foam-studs-waste

   >“除去阁楼地板上的玻璃纤维隔热材料，用喷雾泡沫罐密封所有开口，然后填充纤维素R30水平。安装绝缘的阁楼梯/开口”

   If going that route, unless it's full of rodent crap, just move only the insulation as-necessary for air sealing over the lighting cans, flue/stack/electrical/duct boot penetrations, and the seams of partition walls to the ceiling gypsum, etc, then blow cellulose OVER the pre-existing fiberglass to a combined depth of 11-14". As little as 3" of cellulose over the top makes up for any deficiencies of low density fiberglass, restoring it to it's fully rated performance. You may not have enough headroom to get 14" of insulation all the way out over the top plates of the exterior walls, but that's how much it takes to hit current IRC code minimum in the climate zone 4A & 5A (the cooler half of NC), but 11" (~R38 after it settles) is enough to make it the zone 3A portion.

   The difference in cost between R30 and R50 is much smaller than you might think, and the difference between R30 and R38 is smaller still, especially if it's an over-blow rather than a full replacement. And it's WAY cheaper than insulating at the roof & rafters, no matter what method is use.

   Brian's suggestion about air sealing the attic floor is right- that's really Job #1 and the best bang/buck, followed closely by air sealing (and insulating) the lowest level of the house, whether it's a full basement, crawlspace or slab-on grade. The highest and lowest leaks in the house are the most important, since that defines the total stack effect pressures that drive outdoor air infiltration rates. Verifying/rectifying any air leakage in the new duct system & air handler unit comes next, since even a perfect duct design duct leakage creates room to room air pressure differences that will drive outdoor air infiltration whenever the air handler is running.