The low energy timber frame solution that costs just £80k...

Note - this blog was first submitted to e-news source Place North West for their Green Week feature.

At _space group, we have been working on an intensive research and development programme in which our aim was to develop a housing model both environmentally friendly in the strongest possible terms, and cost effective. The result of this has been Spacehus – our timber framed, offsite manufacture, modular building, which complies with the Sustainable Homes Code at level 4 and can be delivered for £80,000.

The costs have been broken down into three areas – materials £51,000, labour, £16,000 and plant/overhead/profit, £13,000. We have not included land purchase costs or site infrastructure in this price (however we have accounted for a raft foundation solution), as part of our goal with Spacehus is to encourage collaborative working. While the site infrastructure is not included in the cost, we have calculated onsite labour costs, and these are greatly reduced thanks to the offsite manufacture nature of the scheme. Not only does this have the clear benefit of being able to reduce site time to just 20 days, the eco-benefit is that we are delivering a scheme that drastically reduces the associated waste and pollution normally seen on site during a traditional build.

What makes Spacehus different is that we used manufacturing principles to develop it. We looked at techniques used in the automotive and aerospace industries, and we found that an offsite manufacture approach is an environmentally sound one, with this assembly line approach being more efficient, saving time during pre-construction and creating fewer components, which saves on waste and excess building parts. Indeed, each Spacehus is made up of just 19 components, with separate bathroom pods that are fitted during the process.

We have opted to focus on using an integrated, limited supply chain for delivering Spacehus. Cutting down on suppliers provides significant eco benefits as each part of the manufacture and assembly process generates fewer carbon miles.

Swedish timber framed housing manufacturers Trivselhus have developed a Climate Shield for the concept, which provides the building with a tight external envelope, dramatically cuts internal energy waste and helps us to provide potential Spacehus owners with what we forecast to be energy bills of just £10 per week.

We are using UK manufacturer EJ Badekabiner to create the bathroom pods, as well as the roofs and floors and we intend to use our own construction company, _space build, for the assembly, ensuring that the team constructing the scheme are familiar with it from inception.

We have used an efficient condensing gas boiler to heat the building. We spent considerable time deciding on the best heat source to use, as we needed to balance capital cost with energy savings.

With the gas boiler the house costs £10 per week to run. It is also possible to retro fit photovoltaic panels to the roof through a feed in tariff investment arrangement. This could potentially supply the electricity for the dwelling, meaning the only cost would be £2 per week for gas.

This approach is the future of the industry as it illustrates how both the housing and construction industries can bounce back from a time of crisis with a solution that is leaner, greener and better for the environment.

The future is Spacehus - a visualisation of a potential Spacehus scheme

Spacehus - the 21st century pre-fab

Today, architects are re-examining the idea of pre-fab – once a by-word for cheap but disposable and visually unappealing housing – as a new form of low energy, sustainable design.

Spacehus is a unique interpretation of pre-fab, off site manufacture and is based on the principals of PassivHaus. It turns traditional construction methods on their head in several ways, initially by starting construction of each timber-based building with its triple glazed windows and building out, rather than building a shell, leaving a hole for the window and sealing it with mastic. This method ensures that an airtight seal is achieved, with the timber for each Spacehus being engineered to a high level and component gaskets factory fitted.

Each Spacehus is fabricated in Sweden and then assembled on site. This means each building can be created to each Client’s individual specification. With modular building, site time is reduced to four weeks, and each building has a reduced target cost of circa £95,000, providing value for money at a time where housing is in high demand but budgets are tight.

A key focus of each Spacehus is minimising energy use. Not only does each Spacehus fall in line with Part L Building Regulations, each one has the ability to achieve code six of the Code for Sustainable Homes and can be zero carbon.

The particular energy supply that the Client specifies is ‘bolted on’ to the building, which means that using renewable energy sources is a viable option, with Client budgetary requirements being the only barrier to the final energy source and code achievement. The windows and high levels of insulation enable the energy generated within the building to be retained. Heating is provided by a single radiator and two towel rails, with a mechanical ventilation heat recovery system recapturing and re-circulating warm air. This strategy is a very simple, yet effective way of reducing energy consumption and carbon emissions.

Spacehus bathrooms are made in pods, which are pre-positioned on site with the rest of the structure assembled around them. This ensures the homes are watertight in a day and helps to speed up the construction process.

We believe that this design has many varying applications. The efficient construction methodology, low cost per unit and conformation to current building aspirations mean that they are a viable social housing option, while the design could also be modified to accommodate the needs schools have for additional housing, as previous incarnations of the module have done.

Today’s modular buildings should be monuments to the best of what creative design can offer. We are confident that Spacehus is at the cutting edge of a new stage of modular housing and are looking forward to seeing its many applications be put to great use.