We opened the container yesterday and unwrapped them…They look great…frameless, triple insulated glass and elegant rectangular wood frames… photos coming next week!

What you see in this photo is the Concrete Masonry Structure with the 8″ thick EPS insulation. Thick walls!

We started working on the design of a new building which is again somewhere on Pacific Street. Again we are using our exterior circulation concept, but this time we are making the attempt to build a Passive House! Above is the first exterior sketch. More to follow…

While we won’t disclose yet where we found them, as the deal is not completely worked out, we can’t resist to show off the stylish windows we found. And to make it even more interesting please look at the performance data for a casement window (test size ~48″ x 58″):

• Uglass = 0.6 W/(m2K) or an R-value of 9.46 (hr.sqft.F/BTU)
• Uframe = 1.38 W/(m2K) or an R-value of 4.11 (hr.sqft.F/BTU)
• Uwindow = 0.83 W/(m2K) or an R-value of 6.84 (hr.sqft.F/BTU)
• SHGC = 0.48

Not too bad, isn’t it?         ; )

photo credit coming soon.

What looks a bit like a racing stripe running horizontally around the top of the building is actually not decorative; instead it addresses a problem that we, and i guess many others, completely overlooked: a C.M.U. parapet wall is a massive thermal bridge!

What normally happens: The structure of the building is constructed of concrete, and the walls and roof are insulated on the exterior. This is absolutely a good thing, as exterior insulation is far superior to cavity insulation of the interior stud walls.  What has been historically overlooked, however, is the fact that by not wrapping insulation all around the 42″ high parapet (NYC building code) we create a huge cooling rip for the building. As you can see in this Therm model (heat transfer modeling software), the upper corner is much cooler than the other interior surfaces and so condensation is more likely to occur here (grey: concrete, yellow: EPS, blue: XPS).

One way to solve this problem is to use a different concrete-based material which has a similar fire rating to CMU but is a much better thermal insulator: A.A.C or Autoclave Aerated Concrete! AAC has an R-value of up to 1.25 per inch, compared to 0.07 (hr*ft2*F / BTU*in).  This is quite easy to see in the different isotherms:

Here’s a last close-up shot how CMU and AAC come together. The metal strip you see in the photo is the flashing detail which will terminate the roof membrane later…

(Wolfgang Feist is the founder of the german “Passiv Haus” Institute)

1. You can’t open the windows in a passive house (PH).

On the recommendation of the PHI (Passive House Institute) every passive house has windows which can be opened. The technical house ventilation system brings fresh air in, so you won’t ever find any stale air in the house, even if you dont open the windows for an extended period e.g. during cold rainy weather.

2. Due to controlled living-space ventilation there is a draught.

The ventilation of the living space “ventilates” just as much as is necessary for sanitary first-class air quality. It’s best to build air exhausts at ceiling height, and therefore from as little a distance as 30 cm away the air flow will no longer be noticeable; you won’t feel any draughts in passive houses.

3. A PH has no heating.

As a rule a passive house needs only a small heating installation, but it isn’t a’zero heating energy house’. Yes, a passive house has heating.

4. A PH is always rather “clumsy”.

Where does such a statement come from? There are thousands of passive houses in different shapes and sizes: from partial hip roof houses, to those like truncated cylinders and cones, to those in wankel-piston form .There is a wide variety available.

5. The technology is still in development.

A passive house doesn’t require as much technology as a conventional house! The only special technology which is needed is house ventilation with heat recovery, and this has been successfully used in Canada and Scandinavia for over 50 years.

6. You can only build a PH on a sunny site.

Well, this opinion might be the result ofa mix-up with the “passive solar” approach. You will find passive houses on inner-city premises with the housefacing north. A shaded site is no excuse not to build apassive house.

7. A PH is much more expensive than a conventional house- it doesn’t pay off.

Our last inquiry showed four to eight % more investment was required initially. You also have to factor in higher financial aid due to the positive environmental nature of the house. The most impressive result comes later:

Residents will save between 800 and 1500 Euros inrunning costs every year. If you calculate this rationally and look ahead, you will see that you really can’t afford a less efficient house.

8. A PH is always cold .

There is only one thing you can do:

go and visit a passive house. Inhabitants of passive houses like the warmth;

we have measured temperatures between 22 and 240 C in winter. This is affordable, as heating a passive house doesn’t cost a lot.

9. Separate rooms can’t have different temperatures in a PH.

That is up to the inhabitants: you don’t really need cold side rooms if it costs little to keep them warm, and a cool wine cellar can be built into apassive house, if required. Almost anything is possible.

10. You can’t redevelop an old house into a PH.

This is generally true, but it’s only half the story: you can build passive house technology into an old building – it  takes good exterior insulation, tripleglazing and ventilation with heat recovery. You won’t reach the energy standard ofa passive house (With its 15 kWh/(m2a)), but you will get between 20 and 35 kWh/(m2a ). Be clear about this though: real passlve house redevelopment’s are possible, even for bigger properties.

After weeks of figuring out thermal bridge problems, thinking about how to address the existing buildings next door, doing solar gain studies, and recalculating the PHPP modeling in metric, we also updated the exterior of the building… all this while the contractors completed the CMU structure…. please see the our website for more

While a passive solar gain is not required in a Passive House, it has substantial impact on the envelope of the house. Better sun exposure let’s us use a bit less insulation and more affordable windows. As this project is located in an urban area we trying right now to calculate how much help we can expect from the bright NYC winter sun. The photos above were taken from the lower residential floor of the building approximately in the middle of the large south facing rear glass wall. The light blue curve represents the sun’s path at winter solstice and the yellow line is the sun on March 21. What we can see on the graph is that at this floor we only have direct sun on 12/21 from about 10:45AM to 11:45. This is only an hour and the sun radiation is further reduced by the large trees in the neighbors rear yard. We expect to have a much better exposure in the floor above but to easily verify this on site we have to wait another couple of weeks until the next floor is built. (yes, i know that this can be done by calc’s too but it’s fun to see it in the real world) While the December solar gain data does not look to good it is important to note that the required heat demand in NYC is much higher later in the winter… mid January and Feb-March when the Solar Elevation is already higher.

time to give some credit:

thxs to David White to point out his concerns about the importance of verifying the shading data in the PHPP and also thank you to the guys at ozPDA for making such a cheap and easy to use iPhone application called “Sun Seeker”

more about this project

We think this deserves it’s own post rather than an update. After our tedious attempts getting the right U-value data from US based SeriousWindows to be able to use their windows in our PHPP calculations about a month ago i just stumbled across the updated data on their website. And it’s all there: Different window frame and glass U-values and solar gain coefficients. Somebody in this company must like Passive House. Thank you!

here is the link to it

You can download the PDF to see the table with the window/frame/glass specs.