Five towers on the Chalcots were lucky to be selected for the £150M PFI retrofit 4 year makeover works, or at least the residents had hoped would be the case.A different story is now slowly emerging that sets the tone of building problems to come over the 15 year PFI contract period.
Click photo left and you will just about be able to see the panels peeling off !
Question: What does a contractor do when faced with an output driven specification to deliver to a quasi "Decent Homes Standard".
You have probably guessed the answer already; build to that standard, especially as it only represents the minimum standards that builders can get away with.
The output specification is met and the client Camden is satisfied.
It now turns out that the cladding system and metal window system which only just meets the thermal insulation levels to pass current building standards is inadequate. As I have reported in previous blogs during the "cold winter snap" levels of condensation on the metal window frames have been unacceptable and black mould fungus has been popping up (mostly on the silicon sealant) everywhere in many of the resident homes during the past months, more are being reported to me every week.
I have started to dig around in the details of the window specifications themselves, it is clear to read that the windows used are the minimum specified by Schüco. That is not to say that the windows are bad but indicates that in the environment for which they have been installed is unsuitable.
All windows are made to a “thermal insulation” standard. A basic solid wood non-insulated frame provides about 1.4W/m2K. Double glazed glass with argon gas is rather better at 1.2W/m2K. (The lower the U value the better the insulation).
However, here is the rub the Schüco window frames installed on the Chalcots are around 3.9 W/m2K which represents a very poor level of thermal insulation. Which when you take into consideration the exposed nature of the “five” towers facing the Primrose Hill, leads to a thermally inefficient design that HAS already presented all the classic signs of high levels of cold bridge condensation on the metal frames.
As important is the increased energy costs to heat these new refurbished buildings, energy is basically going out the window and with it an increased CO2 footprint for Camden. Compared to what could have been achieved with improved insulation provision.
To add double insult to all the residents of the Chalcots, heating cost are set to increase by 13% over the year for Camden housing properties.
One of the key “selling features” that was used to get buy-in from the 717 resident homes was the fact that an energy efficient saving design was put forward.
Also the level of thermal cladding itself is only what has been described to me as a bare minimum, the architects HTA publicly state in press articles that their design concept is “London Borough of Camden is aiming to deliver a 30% cut in CO2 emissions”
When one considers that the original 40 year old buildings with high prevailing winds facing the Primrose Hill with no double glazed windows (using only one single sheet glass) literally losing up to 50% of heat through the old single sheet windows and cold concrete walls. Then 30% reduction represents only a small improvement of energy efficiency in the wider perspective.
Yes it is a welcome improvement but does it represent good value for a £150M PFI project that is the big question still to be answered.
Author: Nigel Rumble 20 January 2009
