更多的建筑科学
In mylast article，我讨论了ACCA手册J，工业标准计算了设计加热和冷却负载。这些设计载荷表示房屋在非常冷和非常热的温度下保持舒适的加热和冷却量（在BTU中）。负载计算为选择加热和冷却设备提供了基础。为实现最佳的舒适性和效率，所选择的设备必须既不太大也不太小。
Manual J considers heat losses and gains through opaque surfaces like walls and ceilings, through windows, skylights, and glass doors, through infiltration (air leakage) and mechanical ventilation, and, for cooling loads only, heat gains from people and appliances. It also adds losses and gains from ductwork passing through unconditioned spaces.
在本文中，我将深入挖掘手册j计算渗透负载。负载计算软件可以轻松处理渗透作为“黑匣子”;用户删除了几下咔嗒声，软件休息。但渗透是热损失和收益的关键组成部分;在较老的房屋和寒冷中，通常是冬季热量损失的最大来源。渗透输入中的错误可能导致超大或缺乏尺寸。了解驱动渗透的过程 - 以及这些过程如何转化为加热和冷却BTU - 可以帮助HVAC设计人员提供一致的好结果。
Infiltration basics
In winter, outdoor air leaking into a house needs to be heated to indoor temperature. In summer, outdoor air leaking in needs to be cooled and, in humid climates, dehumidified. (Because it’s the air leaking in that must be conditioned by the HVAC equipment, Manual J focuses on infiltration. The air coming into the house is balanced by an equal quantity of air leaving the house through exfiltration.)
For air to move into or out…
6 Comments
哇，深入信息！就如何影响热/冷却负荷的常见问题，您是否可以给出最重要的物品清单到地址？空气密封似乎非常重要，基于此分析和人们的建议/经验。将阁楼绝缘从Say R20提高到R60撞击载荷的增加多少？如何将地下室墙从NONE绝缘到R12左右？
This is going to vary a lot depending on your climate and house design. In general, heating loads are dominated by air leakage and by low R value surfaces. Because surface heat loss is proportional to 1/R, you get a lot more benefit from taking an R-5 surface to R-10 than from taking an R-20 surface to R-60. Cooling loads are usually dominated by solar gains. If ductwork goes through unconditioned spaces, duct losses and gains can also become a large component of both heating and cooling loads.
一种探索如何影响特定项目的一种方法是使用LoadCalc.net等免费的在线计算器（这不是真正的手动J计算）。您可以模拟“基线”房屋，然后查看不同的改进如何影响设计负载。
thanks for the reply. that makes a lot of sense - focus on getting a base level of R after air sealing for biggest bang. i need to play with a calculator some.
Great work, Jon
你做出这个非常重要的声明。
"One point worth considering is that indoor-outdoor temperature difference enters into this calculation twice: once when calculating stack-effect air leakage and a second time when converting air leakage to Btu. This means that heat loss from air leakage increases exponentially with temperature differences. A 10% increase in ΔT could lead to a 20% or more increase in infiltration heat load."
这就是为什么加热系统可以在设计温度条件下挣扎。新建建筑或能源改造的细致空气密封是花费很好的花费。
谢谢，道格。我总是习惯于认为加热需求与ΔT线性增加，但我开始意识到我们需要考虑一些非线性效果。
Hi,
Great article.
I would like to correct an important mathematically error in the article.
The heat loss due to stack does _not_ depend exponentially on Delta T.
It (just by reading the formulae) depends on DT^3/2 power, so super linear and sub quadratic. (I'm not sure that 3/2 trend has a special name).
如果比例常数为1，则DT的10％增加将产生〜40％的热量损失增加。
也是一个问题。如果您对表单的多点回归，您可以通过本文学习与有效泄漏区域相关的常数：https://eta-publications.lbl.gov/sites/default/files/12891.pdf
（请参阅第3页顶部的EQ（1）的描述）。
有什么关系？
EDIT: The link you referenced answers the question:
ELA4 = 0.2835 x C * 4 ^ n
Here C,n are the parameters estimated in the multipoint blower door.
For me C = 210.6, and N=.695 so this method produced .2835*210*4^.695 = 156 sq inches of leakage or 1 sqft. slightly lower than the 176 sq in by the multiply CFM50 by .055
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