In this brave new era of eco-experimentation, designers across the industry are at their drawing boards, and companies are investing heavily, developing the ‘green’ technologies that will form the building blocks of the future. In our practice we are spending more and more time researching green issues. Each project is different from the next; each has a new set of criteria and a new bespoke solution to research. Architects have to invest this time to stay ahead of the game but, while building regulations permit it, the reality of low-carbon building for the construction industry and, importantly, for clients, remains a case of ‘conscience vs cost’, and it rarely comes as a surprise to us when clients with initially high ambitions for an ‘eco building’ lower their sights when the estimates start coming in.
Our approach to sustainable building is in part defined by law, in the form of building regulations, and in part by the desire of our generation to create buildings that have a ‘light touch’ on the environment. However, we are constantly aware of how often these ambitions, as well as the expectations of polic- makers, don’t match the budgets of our clients. Put simply, making low- or zero-carbon buildings still costs much more than making buildings that just pass muster. And it’s understandable (particularly within the domestic private sector) that clients look to save on build cost – even though a low- or zero-carbon building will save money or even make money (by selling power back to the grid) – given the length of time it takes for any financial return to become apparent.
A January 2008 study of the legislation being introduced by the Code for Sustainable Homes (CSH) found that the cost of the highest performing home (CSH level 6: zero carbon emissions) was 240 per cent higher than that of a building built to current standards (CSH level 3). That it may be mandatory to build houses with zero carbon emissions by 2016 gives some idea of the challenges facing the construction industry. Indeed, many commentators refuse to accept that such lofty targets will be achievable, particularly if, as widely expected, the economy of the next few decades fails to reach anything like the dizzy heights so recently experienced.
Despite all this, we are excited by the opportunities a truly (and enforced) green approach will bring to the built environment, and we wholeheartedly endorse the attempts to haul outdated UK construction standards into the 21st century. The case-study project we are presenting is for a low-carbon, detached dwelling in Ipswich, Suffolk. The designs for this house have recently been submitted to the local planning authority, and we hope that a description of the ‘green’ aspects of the building will serve to outline our approach to sustainable construction.
Our clients asked us to design a house for an elderly relative, to be built on land adjacent to their home. Our proposal is for a single-storey building that is sustainable, adaptive, robust and of a manageable scale. The layout of the dwelling has been designed to meet criteria defined by the ‘Lifetime Homes Standard’, a set of guidelines (currently voluntary) that allow buildings to be designed with a high level of flexibility in terms of future adaptation, to provide for the changing needs of occupants over time.
The basic construction will be timber-framed. It is the intention that the external and internal walls be constructed away from the site. The use of prefabrication reduces the embodied energy (mainly in transport) associated with traditional on-site construction. Prefabrication also considerably shortens construction time on-site in the erection of the building envelope, reducing noise and disruption to neighbours.
Super-efficient insulation will be provided to the walls, roof and floor, retaining heat in winter and helping to keep the building cool in summer. Internal partitions will also be insulated, enabling rooms to be heated on an as-need basis, using energ- efficient radiators. The building’s external envelope will be constructed to be air-tight (controlled ventilation aside) to improve thermal efficiency. It is our intention that the building will achieve a standard of insulation whereby space heating is not generally required, save for periods when outdoor temperatures are very low. In all cases, the level of insulation will well exceed current building-regulation requirements. To this end, factory assembly of the main building elements allows a higher degree of accuracy and efficiency in the construction of the envelope.
Low-energy light fittings will be installed throughout the house, together with energy-efficient white goods in the kitchen and utility room. It is proposed that the electricity be supplied to the dwelling on a ‘green’ tariff. The showerhead and all taps will be fitted with regulators, and the WC cistern fitted with a dual flush for lower water consumption. All these items are now widely available, and should be considered the norm in new buildings. Provision will also be made to incorporate future geothermal or solar power water heating to generate a proportion of the property’s hot-water supply, and provision for the future incorporation of photovoltaic panels will be made, should future occupants choose to adopt these technologies.
A sedum roof is to be installed, which will help improve the thermal efficiency of the building. Together with the green ‘living’ façade (included, in part, in response to local planning requirements), this will create an ecological microclimate of benefit to the urban ecology and biodiversity of the area. The ‘living’ wall and roof will bring other benefits, including the mitigation of ‘urban heat island effect’, air filtration to help counter pollution, and storm-water attenuation. A rainwater harvesting system is proposed to serve WC cisterns, washing machines and garden irrigation. All hard landscaping will be permeable, to allow for a natural infiltration of rainwater.
We are mindful of our clients’ budgets. Our inclination is to spend as much as possible on a building envelope that is highly efficient thermally and adaptable internally. With this in mind, our approach can be summed up thus:
- Extremely high build quality, best achieved using off-site prefabrication where possible. High standards of insulation, design and detailing, quality construction and materials.
- Space planning to take advantage of solar gain and natural ventilation.
- Pragmatic, bespoke approach and the avoidance of ‘eco-bling’ for the sake of it.
- Flexibility/lifetime homes standards: built-in adaptability.
- Embracing new technologies where appropriate, and making provision for their future incorporation as they become economically viable.