Wednesday, August 4, 2010

Windows - Thermotech vs Others in PHPP

I went through detailed modelling of the thermal envelope recently and compared Thermotech windows to Euro-style PH windows:
Here's an email I sent to Stephen Thwaites of Thermotech about the results:

Dear Stephen and Ken,


Our design is a 2.5 storey house 41.5ft e-w by 36.5ft n-s. It is a rectangualr box with a gable roof, the ends facing e-w. Very simple and compact shape, with basement. 35 Openings totalling 39.9Sq m of windows, including 4 doors with 1/2 lites and including door and window frames, 20.9 sqm of that on the south.

What I found is:

1. Compared Thermotech glass to a high-performance 'Low-E 0.51 Neutralite Guardian Luxguard (item 35 in the PHPP)' glass with SHGC 0.51 and Ug 0.51, the model showed a 1kWh/m^2an advantage over the Thermotech 322Gain+(75/68) glass. With Thermotech glass, we were at 12.966kWh, and with the Neuatrilite, it was down to 11.99. This compares to the 15kWh/m^2an threshold to be a passive house. The comparison was done with the Thermotech casement frames in the model.

2. Returning the model to the Thermotech glass, I compared Thermotech frames to Optiwin Solarfassade frames, but keeping the 4 doors as before, which are generic. The narrowness of the Thermotech frames (0.68m compared to Optiwin's 0.100) is definitely a significant boost to performance.  Switching from Thermotech Casements all around to the Optiwin degraded the building's performance from 12.97kWh/m^2an to 14.81 - a very significant difference. Fixed (non opening) Thermotech windows will be good as well, of course, though there is still more comparing to do.
I didn't look at the sliding glass doors since I don't think they'll meet airtightness needs without the lift and slide hardware.


1 comment:

  1. I've told that Inline and Thermotech have the exact performance if using the same glass. Only difference is price and variety of product...