How do you turn a grotty, dilapidated four storey Victorian house so leaky as to be beneath pressure testing into a Code Level Four equivalent?
The project Camden Council took on aims to show how Victorian dwellings can be refurbished to address both heritage and energy so that future generations can take pride in their architectural heritage without seeing them as an environmental burden.
Number 17 St Augustine’s Road (in a conservation area) is owned by Camden Council who are refurbishing it for social housing. Over half of the housing in London is of solid wall construction. Much has heritage value (60% of Camden is within Conservation Areas). Solid wall houses on average have almost double the emissions of those built to current Building Regulations. It will aim to reduce emissions by 80-90% based on normal use. UCL will monitor the house during construction and occupation, including monitoring of temperature and humidity in walls, pressure and a survey of fuel use by neighbours.
The original house built in the 1850s had thermal bridges galore along with surreal and idiosyncratic décor. The house was so leaky air pressure tests could not be performed.
Chit Chong, acting energy and sustainability manager at Camden Housing notes the dynamic tension between the need for emissions reduction and the need to preserve heritage.
“Decisions such as the design of the wall insulation should not be being made by heritage consultants without involvement from people with expertise in building physics and engineering. (Conversely, decisions about heritage should not be being made by engineers without the involvement of people with heritage expertise.
“Full compliance with the energy efficient requirements of the Building Regulations would unacceptably alter the character or appearance of the building”
Chong stresses that a building can last up to120 years and it is a “machine which generates emissions”.
Practice
Some of the issues over installing renewables involved cost, health and safety issues. A crane would have been necessary for installation of ground source heat pumps, and the underfloor system would have required continual maintenance. Overcladding was an issue because of heritage – the whole street façade is brick. Also one wall was a party wall which would have been problematic. Wood wool, the favoured choice of some for the insulation material would have taken up too much room to achieve the reuqired thermal performance.
In the end the key was to go for deep internal insulation, with the need for energy performance outweighing the need to keep cornicing and fireplaces.
Chong puts it into perspective; integrating a new efficient boiler along with wall insulationand glazing to Part L would result in a 64% increase in energy efficiency (only one in five new homes meet latest Part L standards).
Double glazing, high insulation with the addition of solar thermal would bring a 74% increase.
And the addition of 3.5kWp PV system would bring it to 81% efficiency.
Construction on the project started in January 2008. However the roof needed to be replaced and internal walls strengthened, which added to the final projected cost including renewable technologies of £340,000.
Contractors Lengard set up Toolbox talks to stress to operatives the importance of good practice to avoid poor air gaps and cold bridges. Plasterboard was stripped back to brickwork, battens fixed and all the external walls were internally lined with Kingspan Kooltherm K18 insulated plasterboard up to 95mm thick with integral vapour barriers. To avoid cold bridging insulating foam was injected around the joists of first and second floors.
The floor was insulated using Kooltherm K3 Floorboard laid over a concrete slab and around the perimeter.Two layers of Kingspan Koolthermn K7 Roof Board was fitted to the sloping roof space and carefully sealed. Nilvent breathable membrane was laid between and over the insulation.
Windows and ground floor doors were remade by MH Joinery and Russell Timber Technology to fit the traditional appearance, but draught sealed and using Pilkington double glazed units, argon filled and with low emmisivity coatings to give a U-value of 1.5w/sq m/k, 40% better than normal units.
Small Ventaxia heat recovery units in kitchens and bathrooms capture and transfer around 80% of the heat from the outgoing stale and humid air to the incoming fresh air.
A Worcester Bosch Condensing Boiler with good controls was installed, together with a hot water cylinder that also links to the solar thermal hot water panels on the roof.
Worcester Bosch thermal solar panels on the roof are estimated to save 40% of annual hot water heating.
SunDog Photovoltaic roof panels will supply 3.5Kwp to the house which reduces electricity loads. Megaman low energy light bulbs are fitted throughout the house reducing CO2 for lighting by around 80%. The house is 20% above new build standards of thermal performance; B rated on EPC and equivalent to Code Level 4 of the CSH.Chong points out that the best value gains are from the wall and roof insulation.
John Doggart, chairman of the Sustainable Energy Academy at the launch, put the Camden refurbishment into context stressing the need to convert large numbers of existing houses to get anywhere near national carbon targets.
However he said current obstacles included lack of motivation; lack of knowledge; doubts over delivery capacity