Paul Ensch, director of Innovare Systems, is so enthusiastic about the company's demonstration house at the BRE's Innovation Park that, if he could, he would pick it up and put it on a plot of his choice. People do tell him to stop going on about the building, he said, but, well, he just can't help himself.
The subject of Ensch's attention is the structural insulated panels (SIPs)-based Jabhouse Innovare's response to the need for affordable housing and the emphasis by registered social landlords (RSLs) on innovation.
Jabhouse, a "whole house system", is the result of a partnership between Innovare, a subsidiary of construction company Osborne, and SIPs distributor Vencel Resil Ltd. Innovare was initially attracted by Vencel Resil's pitched roof product Jabroof Slimfix which had never been used in the UK. The company trialled it on a block of flats for the Chichester Diocesan Housing Association: a roof that would normally have taken a fortnight was up in just two days. As well as the benefits of speed, the structural panels mean there is no need for roof trusses, providing space for a room in the roof or a large storeroom.
Recognising the potential, the two companies worked together to develop a panel system for the rest of the structure.
They had the panel," said Ensch, "but they hadn't dealt with how it juxtaposed with other parts of the building or approvals.
The result was the Jabhouse a combination of a structural shell of SIPs panels, Jabroof, floor cassettes and internal walls. A pilot project of three houses in Sompting in West Sussex satisfied the requirements of the Building Regulations and more than satisfied the client, the Southern Housing Group, which presented Osborne with an award for the speed of construction, the reduced number of defects and the modern methods of construction (MMC). The occupants were also pleased with the result. "Over nine months, one resident's heating bill was £60," said Ensch.
In the past year other housing associations, such as Portsmouth, have included Jabhouses in their developments for the very reasons that Southern Housing gave Innovare the award.
The appeal can be seen in the BRE demonstration house, which will officially open this month. Comprising two floors plus a room in the roof, the house was completed in just 12 weeks, with the walls, floors, roof and internal partitions all constructed from FSC- or PEFC-certified timber going up in just one-and-a-half days.
Ensch points out that while MMC gives speed of construction, it's things like good logistics that tip the balance: only three deliveries to site are required for every four Jabhouses built.
And while Innovare has its logistics down to a fine art, the demonstration house also illustrates how the Jabhouse is pushing the boundaries: in terms of energy efficiency it exceeds Part L of the Building Regulations by around 40%, and Part E by 10%. The SIPs comprise 130mm of expanded polystyrene bonded between two 12mm layers of OSB3, with an extra 50mm layer of insulation (both inside and outside) and battens added to form a service zone between the panel and the plasterboard. All this achieves a U-value of 0.15W/m2K, while the triple-glazed timber windows from Swedish Timber Products have an average U-value of 0.8W/m2K, the walls are 1.4, the roof 0.1 and the floor 0.16. The result has earned an EcoHomes rating of excellent, although Ensch points out that this is affected by location.
A Jabhouse exterior can be clad in any material of the client's choice. Innovare have demonstrated this on the BRE house with untreated Siberian larch, softwood with a Sadolin finish, Ibstock brick, zinc and a slate lookalike made from recycled tyres or plastic bottles. α
ά As well as the good insulation qualities of the SIPs, their energy efficiency can also be attributed to their 6x2.7m size. "Because the panels are large, there are fewer cold bridges and fewer opportunities for air leakage," said Ensch. Air changes in the house, which has a Greenwood heat recovery unit, are only 1m3/hr/m2 and it uses one-third of the energy needed for heating compared with Building Regulations requirements.
Until now the SIPs were manufactured in Germany but Innovare's own energy impact is being reduced as Vencel Resil will open a manufacturing plant in Howden, Yorkshire, in July.
While the SIPs enhance energy efficiency, they also reduce waste. The lightweight structure of the Jabhouse requires less heavyweight foundations, reducing the amount of soil removed from site and the quantity of concrete used. And, as the SIPs are manufactured with pre-formed openings for windows and doors, including strengthening to distribute loadings, there is virtually no waste on site. "The only waste is bracing across the doors, which gets cut off," said Ensch.
But it's not just the building system that is a selling point for Jabhouse. Innovare takes responsibility for co-ordinating the design, supply and construction of the house and is the single point of contact for the client. This is achieved by its close relationship with its supply partners. Everyone in the supply chain attends the monthly operations meetings and the next step will be to adopt integrated software.
Innovare also intends to develop the Jabhouse concept further. "We don't want to leave the product there," said Ensch. This may include window installation, external and internal finishes, developing the already sophisticated whole house wiring system and extending the BBA certificate from three storeys to four.
While MMC have drawn some criticism for being inflexible, the SIPs are bespoke for each design, which actually adds flexibility, said Ensch, and the fact that only the external walls are load-bearing means that the internal configuration can be altered as the occupants' living requirements change.
"Every house that Osborne has built since 1991 is different and Jabhouse is very adaptable, he said.
The demonstration house, designed by Baily Garner, is effectively a rectangle but the monopitch roof gives it a jaunty profile and the interior spaces, angles and finishes lift it beyond its simple shape.
"It's simple but it has a lot of vibrancy," said Ensch, clearly showing his enthusiasm again.
With the right designer, energy efficient, affordable housing can have imagination and flair, he said. "RSLs don't want their houses to scream affordable housing and that can be done with good design."
