A social housing project led by The Hyde Group, to identify the most practical and effective package of home-retrofit measures to achieve an 80% reduction in CO₂ emissions, is featuring the industry-leading low U-value NTech Passive windows and external doors from NorDan, leading supplier of environmentally-friendly high-performance timber windows and doors.

The project, dubbed Retrofit and Replicate and carried out by The Hyde Group and ECD Architects, with Mears as lead contractor, is taking a typical 1930s estate three-bedroom mid-terrace house in south-east London and applying £80,000 worth of initiatives, designed to reduce CO₂ emissions.

The project aims to identify the most straightforward improvements to achieve the government’s 80% CO₂ reduction target. With the existing double-glazing shown to be the weakest point during airtightness tests, these have been replaced with aluminium-clad timber NorDan NTech Passive triple-glazed windows. These have warm-edge spacers and composite insulated-window frames to achieve an industry-leading low U-value of 0.7 W/m²K.

Mark Elton, associate director and head of sustainability at ECD Architects and specifier for the project, says: “The primary reason for choosing NorDan was of course the very low U-value on the NTech Passive windows and its durability, but also the availability. Most low U-value windows, to this high specification, are only available through niche eco-distributors, which is less appealing to housing associations such as Hyde where we could be looking at a large scale order, ideally from a large UK-based company such as NorDan.

“In addition, if following the trials it is decided that perhaps triple-glazing is not the most cost effective way to go across the full-housing stock, then NorDan can also supply a double-glazed NTech Low Energy window which has exceptional low-embodied energy, plus a whole window U-value of only 1.2 W.m²K.”

The project also features NorDan external doors, the NorDan Hampton high-performance door at the front and a standard rear balcony half-glazed door at the back. NorDan’s high-performance external doors combine the best quality burglar resistant materials with integral strength, energy saving construction and character. This includes double-steel plates, security lock and striking plate along with triple glazed pane, toughened on both sides as standard. The NorDan standard balcony door also has safety features such as 48mm thick panels that cannot be disassembled from the outside, with a U-value of 0.6 W/m²K.

The internal temperatures, ongoing electricity, gas and water usage, in addition to energy used for space and water heating, will be monitored remotely over the coming two years. It is estimated that energy consumption will be reduced by up to 86% with a saving to the residents of around £600 a year.

Other initiatives at the house include improved insulation to floors, external walls and roof, controlled ventilation, an efficient space and water heating system, solar thermal collectors and photovoltaics, low energy lighting and water conservation measures.

The two-year project starts as the government recently announces an amendment to the Climate Change Bill, increasing its commitment to reduce greenhouse gases from 60% to 80% by 2050.