The Brentham Society Committee has posted on the website its report on window renovation. The conclusions are given in the Executive Summary with Guidance for Residents in Appendix B.
The Committee will continue looking at the specifications of conservation quality double glazing units and encourage further discussion in the future.
Find a copy of the report here
Click here for some background.
Brentham Garden Suburb 
Further to my previous comment, on a technical level, this report is seriously flawed.
1) The conclusion to be drawn is that one should let ones house windows rot to the point of being unrepairable, then you will approve double glazing. Hardly constructive in maintain the short term appearance of the estate or the longevity of the houses.
2) Who defines economically repairable. Do you propose do means test individual house holders. Surely socially divisisve and a gross intrusion on the individuals privacy. One persons economic position is vastly diferent to anothers. Surely you don’t think the Brentham society should be the judge of this.
This report needs seriously rethinking, along the lines of enabling conservation, not preventing it.
I’m afraid it is your comments that are flawed: the Brentham Society does not approve anything: Ealing Council does. Neither does it means test. What it does is to offer advice and guidance to people living on the estate, and that is the purpose of this Double Glazing document. It is written for people with some interest in conservation, whose basic tenets are that maintenance is better than repair, and repair is better than replacement. People intent on installing double glazing will no doubt find ways round it.
What a luddite document. This is about anti conservation, rather than appropriate conservation and demonstrably fails to show that the self appointed people running this group really don’t get it. We wish to have this estate still standing and maintaining its wonderful period ambience in 100 years time.To do so, proper conservation, not a setting in aspic, using sympathetic modern materials and techniques must be permitted. Or should we all reinstall gas lighting, coal fired hot heating and hot water production and reinstall cast iron gutters. Appropriate double glazing is approved for grade 1 listed buildings in Bath and Edinburgh, masterpieces of English heritage architecture. Does the Brentham committee believe they understand conservation better than the conservators of these rather grander buildings than ours? Personally, unless this attitude changes we are withdrawing our (40 year long) subscription to the Brentham society and would invite suggestions from interested residents as to how the estate can move forward with a more democratic and enlightened way of encouraging the sympathetic survival of our lovely estate.
This sneering invective is really disappointing and not at all helpful. Ignoring the nonsense about coal fires, and the assumption that what’s good for Edinburgh must be right for Brentham, let us consider democracy. Last night we held the AGM of the Brentham Society, advertised in the Brentham News, and on the notice boards. Those who attended voted in the present committee nem con. I think that is how democracy works. There are some spare places on the committee if you would like to apply.
It isn’t just about economics – it’s also about comfort. In winter, Brentham houses can be very uncomfortable. Nobody who has lived in a well insulated modern house will want to move to Brentham. In the very long term, this will be a problem for the sustainability of the estate, unless the thermal properties of these houses can be greatly improved.
Upvc will be, ironically, the start of the rot. My daughter had replacement double glazed wooden sash windows put in her house off Northfields and they are draught proof, aesthetically pleasing and keep the heat in. Wherever I go I can spot a mock Georgian Upvc window at a hundred paces! Please keep the wood and appoint an approved supplier and fitter to the estate who will give good prices in return for being first port of call.