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Nottingham University students build the H.O.U.S.E. at Ecobuild in March

Academic hot house
Published:  09 July, 2010

The all-timber, solar-powered H.O.U.S.E. points to the future of eco-home design in more ways than one. Mike Jeffree reports

In June, as most UK students were winding down for a long, leisurely summer holiday, a team from Nottingham University’s architectural department were slaving away in  in hot competition under the beating Madrid sun.

The students were putting together H.O.U.S.E., Nottingham's entry in the international Solar Decathlon, a contest pitting colleges from around the world against each other to design a sustainable eco-house concept that’s powered solely by the sun.

This year’s competition has attracted entries from 19 countries (13 from Europe, two each from the US and China and one each from Brazil and Mexico). However, the Nottingham team, comprising architectural and engineering undergraduates and masters students, is eyeing the prize with confidence, having already tasted success. Showing the completed H.O.U.S.E. at the Ecobuild exhibition in London in March, they garnered not only very positive visitor comment, but also Timber & Sustainable Building’s inaugural Timber at Ecobuild Award.

The show also gave the UK students invaluable experience ahead of the contest of putting the building together under pressure. At Earls Court they had just four days. At the ‘Villa Solar’ competition venue in Madrid they get 10.

But H.O.U.S.E., which stands for Home Optimising the Use of Solar Energy, is more than a showpiece. Under the Solar Decathlon rules, entries not only have to prove their energy performance, they have to demonstrate that they’re the basis of a practical, commercially viable build system.

“H.O.U.S.E. was designed for the UK context and will deliver  a zero-carbon, Code for Sustainable Level 6-compliant design,” said architectural lecturer Dr Lucelia Rodrigues, who was one of Nottingham’s co-ordination team for the project. “But the aim was also a sustainable concept that’s suitable for the mass market and could form part of a sustainable masterplan for a deprived area of Nottingham.”

The student team decided early on to use a timber-based prefabricated system and it was at this point that another key element of the Nottingham entry slotted into place; a close working and consultative relationship with building products giant St Gobain Group.

“They supported the project with both technical inputs and material supply, helping the students’ select materials that fitted with the architectural design of a family home while also satisfying our sustainable ethos and logistical strategy,” said Rodrigues.

The business seemed just as enthused by their participation in the venture, Stuart Mckill, of St Gobain’s engineered wood specialist Pasquill, describing it as a pointer to the future for the timber construction sector.

The finished H.O.U.S.E. attracted intense visitor interest at Ecobuild

“Environmental pressures are producing the biggest changes in building in 80 years and to meet the demands this is putting on the supply sector knowledge transfer with academia will be increasingly important,” he said.

The core of the H.O.U.S.E. are Pasquill floor, wall and roof cassette panels comprising an I-joist and glulam frame, skinned in 9mm OSB3. These contain Multimax 30 insulation with a lambda value of 0.030, from fellow St Gobain business Isover. They also include a layer of the latter’s Vario polyamide membrane, which, says the company, absorbs and releases water vapour according  to climatic conditions to prevent moisture build up in the timber structure.

The floor cassettes incorporate a 65mm layer of Isover Acoustic Partition roll and internally the structure is finished in plywood, to “continue the timber construction theme”, plus British Gypsum Rigidur H fibreboard. The latter provides further thermal and acoustic insulation and was also chosen to give the modules greater rigidity both when complete and during the journey to Madrid.

H.O.U.S.E. uses triple-glazed, aluminium and timber composite windows from AM Profiles and is finished externally, in vertical cladding made from Stellac thermowood, the same material used for the apron of decking. Stellac, supplied by another St Gobain company, International Timber, comprises radiata pine which has been super heat-treated to boost its durability, effectively giving it the properties of a hardwood. Like the other timber elements in the building, it is environmentally certified, in its case under the FSC scheme, and also comes with an audited carbon and energy trail.

Finally, giving the completed H.O.U.S.E. its energy is an array of Avancis photovoltaic panels. These comprise thin-film modules based on copper indium selenide (CIS technology) and cover most of the roof.

Some of the core structural elements of the building were deliberately left exposed to “express the method of construction” and provide a learning tool in efficient prefabrication for visitors. For the students, according to Rodrigues, the whole undertaking has already proved an invaluable education.

“They say they’ve learned more in their few months constructing the H.O.U.S.E than the rest of their academic lives!” she said. “It’s put them in touch with such issues as embodied energy, energy efficiency, user comfort, material selection, construction management and on-site implications of decisions made at design stage.”

Whether the students learned enough to walk off with the 2010 Solar Decathlon remains to be seen. The judges make their decision on June 27.

The building is designed to be all-round sustainable, including an interior courtyard where occupants can grow herbs and vegetables