Tigh Grian presents sector defining, ultra efficient volumetric homes

// the building envelope

Tigh Grian's energy- and waste-efficient volumetric houses are now ready to become homes. After a year of being showcased up and down the UK, these innovative, quick-to-construct, attractive dwellings fight fuel poverty and address the need for affordable housing.

Tigh Grian Ltd is a sector-defining leader in the design and procurement of volumetric homes for mainstream housing in the UK. 2015 has been a stellar year for the company, with its demonstration houses taking their places at both BRE Innovation Parks in Scotland and England, and being made a key focal point at major industry events including UK Construction Week, allowing visitors to investigate these ultra-efficient dwellings and get to know what a volumetric house represents.

Headquartered in Edinburgh, Tigh Grian Ltd was established to develop and manufacture a portfolio of house types that were affordable, offering good space, air quality and relief from the risk of fuel poverty.

With support from the Scottish Government and a major housing association, a project was forged that would take house specification to a very high level of quality and energy performance, while still remaining affordable; and it is the volumetric construction method that is the kingpin in delivering these deceptively simple objectives.

As designed and manufactured, the houses deliver excellent space standards: approximately 50 m sq for a one-bedroom house and 87 m sq and 107 m sq for two- and three-bedroom houses respectively. The predicted annual space and water heating bills are very low at £210.00 per annum for a two-bedroom house.

Tigh Grian’s houses are delivered to site with completed interiors, meaning they are fully wired and plumbed, fitted with kitchens, bathrooms or shower rooms, and fully decorated. Once energised at their final location and cladded with their external finish to suit their local conditions, they can be occupied. This can happen reasonably quickly, as the houses are established on pre-prepared foundations and as there is no requirement for interior access while the roofing and cladding are completed, there is no need to clean up after muddy boots tramping through the interior before their new inhabitants move in.

Efficient use of materials is key to making a Tigh Grian house as waste-free as possible. Using panel and timber claddings as rain-screens not only speeds up construction but addresses an increasing shortage in brick/blockwork skills and materials. Moreover, as a Tigh Grian house is predominately of timber construction, the timber products have the added advantage of locking up captured carbon for decades, while recycled materials form the house's internal linings.

There are numerous benefits to Tigh Grian houses being manufactured off-site, namely the finished product is consistent, there is less exposure to the elements, waste is minimised, and site operation traffic and construction time are reduced, ensuring early achievement of the project price.

At the factory there is a weatherproof environment for the workforce. Quality control is easier and more efficiently applied on a production line and there is an altogether better environment for training apprentices and for the main workforce, as the place of work remains the same - not scattered across the county or further afield.

As with all construction options, there are some drawbacks to counterbalance the advantages. The conventional design and construction process is linear and incremental, and so design and specification decisions cannot be taken to the last stages of site operations, as all decisions affecting the internal design and specification must be concluded well before manufacture commences. 

It helps to liken volumetric housing manufacture to an automotive production line. Everything down to the door numbers must be available at the appropriate point in the supply chain for incorporation into the completed unit. As such, the volumetric procurement process requires a slight cultural change from the norm - both for the client and the consultant - as all decisions need to be made at the beginning of the project, as changes further downstream can be expensive.

Nevertheless, the benefits speak for themselves, which is why Tigh Grian houses will shortly become homes.

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