This section is a compilation of frequently asked questions the association has received over the years, and our answers, composed in the clearest possible language.
The sincerest hope to allay any misperceptions regarding passive house prompted this Note, and as time passes and more data has been collected, postscripts will be added.
But first, before we begin…
Passive House / Zero Energy House … are all buildings and houses.
What then is a house? The answer may require a philosophical reply; however, to start, a house should be comfortable to live in.
Just because it is called a passive house does not negate the fact that it is still a house. In other words, just because it is a passive house does not mean that "energy" takes priority over "man."
If this point is accepted, then questions regarding passive house should be relatively easily clarified.
1Q: To minimize heat loss, do we have to reduce the number of windows and size of windows?
1A: South-facing windows should be as large as possible; East-facing windows, moderate in size; and the remainder, as small as possible but larger than 1m2.
1A Explanation: The sequence of insulation performance is typically as follows:
Wall > Glass > Frame
Since the insulation performance of the window is lower than that of the wall it would seem that reducing the window area would be a good thing. But windows play a different role from walls in that they also admit solar heat gain. Therefore, unconditional reduction is not the solution.
Also, if the window is too small, then the proportion of the glass to the entire window becomes too small, which is not good. Therefore, 1m2 or greater is the recommended lower limit. 1m2 = 1m x 1m, which is not that small a window.
Since the typical opening width of window systems is about 0.75m, to net 1m2 the overall height must be 1.3m. Since this is the minimum recommended size, it can get bigger.
Meaning that windows such as the one shown below are too small.
If making a passive house only required removing windows… houses like the one in the image below would have been developed much earlier.
[Source: : http://blog.daum.net/jamesju_usa/292]
1-1Q: If we have a north-facing house, must we reduce the size of the view facing living room window to 1m2?
1-1A: By no means
If you feel stuffy because the window is too small, it is right to increase the size. The point of building your own house is to be happy, so if a small window is going to make you miserable, go for the larger one. Just remember that if a north-facing window is too big, the amount of heat loss will increase which will require a better performing window to stay warm through the winter months.
1-2Q: Are you saying that we can have large north-facing windows… but then it will not be a passive house?
1-2A: Yes and No.
First of all, our association does not want to declare that everyone should only live in passive houses. A house with no major defects, a house that does not cause you pain is a house which will always take precedence over a passive house. Therefore, even if you cannot achieve the passive house standard because the north-facing window has been maximized, increasing the window's performance will keep you warm from cold drafts and prevent condensation from forming and that is good enough.
But this north-facing house can also be a passive house. It will just cost more. If this is acceptable then it can be achieved; otherwise, let it go. It is not the point to get the "passive house"… but to enjoy living in your house. No need to get obsessed with names. The only wish is for everyone to be able to enjoy a better quality of life for the same price.
1-3Q: What if I have a north-facing house and I want to maximize the north-facing window but do not have the funds to purchase a better high-performance window?
1-3A: Quite persistent with this line of questioning...
Rather than an explanation, a solution is more in order.
Since you will clearly have condensation running down your windows and cold drafts in the winter, the best we can offer is as follows.
First, rather than an ambiguous mid-range priced window system, the double sliding window is better, like the type commonly seen in apartment living rooms. They are technically referred to as "double-pane double glass sliding doors."
Second, if that too is out of your range, forfeit the northerly view in the winter months and cover the window with "bubble wrap" which will ameliorate the situation.
2Q: Is lowering the floor-to-floor height as much as possible and increasing the wall thickness to minimize the usable area the only approach?
2A: No need to lower the floor-to-floor height. Due to changes in the building codes, overall wall thickness has no relevance to the usable area.
I do not know exactly how high one can raise the floor-to-floor height in a house, but if you want high ceilings, I suppose you could raise them to your heart's desire within 6 meters. Very high ceilings result in great energy losses, so those wanting a passive house with high ceilings are usually satisfied with a double height living room space. Decisions regarding even higher ceilings are almost outside the realm of passive houses.
The thickness of exterior insulation is excluded from the calculation of the overall wall thickness. Therefore, overall wall thickness has no relevance to the usable area.
Of course this condition applies to concrete houses with exterior insulation. Houses built of wood; SIP and the like already receive some compensation so this rule does not apply.
Below is an extreme example of usable area. However, it is so common that it is not really actually that extreme.
The example below depicts the real conditions of a country house made of sandwich panels.
A grandmother lives in the house alone; however, she wanted a proper house and because she had limited funds, it was built of sandwich panels for 1,800,000KW/py.
The total area is 22.2py.
This interior image was taken with a thermographic camera. The interior temperature was brutally cold. (View of the kitchen interior)
The bathroom is already frozen.
The problem is that the grandmother installed a heating system in the entire house, but the utility bill was so unaffordable that she spends the winter days in the 5py kitchen, even sleeping there. (Due to the heat generated from cooking, she thought she could save on the heating bill.)
The infrared image of the kitchen floor shows a leak in the XL pipes. It either froze when she turned off the heat when she went out, or there was a large amount of moisture surging from the ground that puddled under the pipes.
The image below is what a radiant heat (ondol) floor should look like.
The result of the airtightness test came out at 1.35ACH/h (@normal). Even with the windows and doors closed, the result is 2.7 times that required by code. It must be painfully cold; however, paradoxically the indoor air quality is quite good.
So the grandmother built a 22py house in which to live but in essence she is living only in 5.3py during the winter months. On top of which, the rooms which got no use during the winter months, remained unused as the seasons changed. It was a virtual warehouse.
"Usable area" is only relevant when the entire house can be used comfortably. The example just given was an extreme one; but it is not far-off from the state of architecture in Korea today.
This shoddy house was ultimately designed by someone claiming to be a professional, who then filed the "permit documents" which another professional then used to "build" from.
Our association is not dreaming of some monumental "co-existing humanity;" just a humble wish that professionals find their proper place to restore market confidence.
2-0Q: The atmosphere here is kind of scary. T_T are other associations like this?
2-0A: We were talking about usable areas and then digressed. Excuse me. Please continue with the questions.
2-1Q: Then what is a reasonable floor-to-floor height for a passive house?
2-1A: The typical floor-to-floor height for a detached single house is 2.7m. Passive houses are no different.
If you would like to have 3m high ceilings, it does not matter.
It is just that typical apartment ceiling heights are 2.5 ~ 2.6m so it would be a good idea to take a look and compare is all. And if you feel no particular discomfort, and the height feels acceptable, then going with 2.5m is good. Passive houses and a certain degree of warmth aside, it is because you will also be able to save on construction cost.
2-2Q: So are you saying that even if the total floor-to-floor height is 6 meters it can still be a passive house?
It is like the window. The insulation just needs to get thicker. Not even that much thicker. Just a little bit more. But, no matter how small it is, it all adds up. If you do not have the means for the additional thickness, you do not have to do it. But, if you have the means to have 6m ceilings, it does not make sense that you do not have the means for the additional insulation that will help maintain the warmth comparable to other homes.
At the risk of sounding redundant, the name, Passive House is not what is important. If you want to feel the same warmth as the house next door while raising your floor heights, then you will have to add more insulation. Our association will be satisfied just by your acceptance of this truth.
So, if you go for the 6m height, but have the same insulation as the neighbor, the same windows as the neighbor and do not expect to have the same warmth or better, then you got the message.
2-3Q: I want 10m floor-to-floor heights. What should I do?
2-3A: T_T. First, you will need a good structural design. Passive House follows afterwards.
When you exceed 9m, a seismic performance assessment will have to be applied by the structural engineer.
3Q: In order to minimize contact with outside air, must the house plan adhere strictly to a simple rectangular shape by which we forfeit aesthetics and beauty?
3A: You can do whatever you want to.
3A Explanation: "What is the standard of beauty" is how the answer should begin; but we will skip the fundamental question. This is also in line with the above answer. If you do not like boxes, so be it. Again, nothing, energy or otherwise is more important than your happiness.
It is only that the more complex the shape, the colder it will be. Just please be aware of this fact. In a passive house for living (versus living for passive house) for your complex shape, thicker insulation to cover the shape, not even high-performance insulation, is recommended because, it is a good thing.
Also, if the shape becomes complicated, the construction cost goes up. It is a choice the Client must make. The association, rather than insisting, is just saying that a simple shape is good for energy performance relative to cost. The association is not paying for the construction cost. The Client has to cough up all expenses.
So, "I do not like passive houses! I am going to live in a house with a fancy exterior," are not the correct expressions. "I want to live in a colder house with a fancy exterior even if it costs more," is the correct expression. There is no reason to drag passive house into this line of reasoning.
Below is a recent example of passive houses around the world. Whether these houses are beautiful or not is up to the viewer. (Note: as you scroll down, the houses get more expensive. Even if they were not passive houses, the same would be true.)
4Q: In order to avoid cooling/heating unnecessary space, must we send everything but the bare necessities into storage?
4A Explanation: It is difficult for even the association to understand the intent of this question. It sounds a bit overstated. If you send everything but the "bare necessities" into "storage" then… what will remain in the house? The situation is no different from a stolen boat right before it sinks. The question is not addressing a "house" and hence, a passive house neither.
5Q: Why is a sealed passive house better than a breathing house?
5A: The typical house, which you are imagining, too is sealed.
5A Explanation: Fortunately, we already have an explanation prepared.
Whether you disagree or not with passive houses, our association has no opinion. But, just as we never claimed that the general house is bad we hope that you will not say that a passive house is bad.
In the end, houses reflect the values of each individual; whatever the house, there is always room for improvement. We are just here to further the studies and lead architecture in a better direction.
It is just that we believe that a better future is passive house.
However, a house with no defects is better than a passive house; a house in which you can feel happiness always takes top priority.
When more questions accumulate, we will add to this Technical Note.
Translated by Alice J Choy (firstname.lastname@example.org)