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Thatched roof meets new tech on one of UK's greenest buildings

Morgan Sindall is overcoming complex requirements and clusters of sinkholes to deliver a new building for the UEA that’s on course for both Passivhaus certification and BREEAM Outstanding.


Project: The Enterprise Centre

Client: Adapt Low Carbon Group

Main contractor: Morgan Sindall

Architect: Architype

Total project cost: £15m


It is extremely challenging to achieve Passivhaus status when constructing a new building. It’s also extremely challenging to secure a BREEAM Outstanding rating.

So imagine how difficult it is to achieve both those ratings on the same build, as well as seeking to make sure your building has one of the lowest embodied-carbon levels of any of its size in the UK.

That is the challenge facing Morgan Sindall in construction of Adapt Low Carbon Group’s new Enterprise Centre, located at the gateway of the University of East Anglia in Norwich.

“Passivhaus on its own wouldn’t be as difficult without BREEAM, and either of those wouldn’t be as difficult without exemplary low carbon either,” Morgan Sindall contracts manager Steve Brock explains.

“Every decision we take requires a lot of thought and discussion.”

Unique vision for local businesses

Adapt CEO and Enterprise Centre project director John French says the concept for the building had been in gestation for some time.

“It’s the first time all these features have been brought together in one place.

“The vision is to produce the greenest commercial building in the UK. It’s been like years of pulling on an elastic band, preparing ideas – and now that we’ve let it go, it pings into place.”

From the client’s point of view, the building is designed to be a place that will stimulate ‘enterprise’, with shared, flexible working spaces providing a place for local start-up businesses to grow and share ideas on the university’s campus.

“The vision is to produce the greenest commercial building in the UK. It’s been like years of pulling on an elastic band, preparing ideas – and now that we’ve let it go, it pings into place”

John French, Adapt

“It will put students and new companies side by side – we think that’s unique,” Dr French says.

The building footprint is 3,400 sq m and will be able to provide support to more than 600 businesses, while creating 250 jobs on the site.

As well as space for businesses, a 300-seat lecture theatre will sit in the centre of the building, putting students alongside the start-ups.

The green ethos extends to the materials used, too, with Corsican timber sourced from nearby Thetford forest and reed from Norfolk and Suffolk used for thatching to create what Dr French describes as “East Anglia in a building”.

From forest to site

The timber from Thetford forest had never been used in this way before, Mr Brock explains.

“This was the first project to take timber from there for construction,” he says. “Previously it was used for lower-grade purposes like fence posts and pallets.”

The building’s south wing contains 100 per cent timber from Thetford, the link section has 70 per cent and the north wing 40 per cent.

“All of the reed used here comes from local sources – a lot of reed used in thatching elsewhere comes from Europe nowadays”

Steve Brock, Morgan Sindall

Timber was purchased and shipped to Ireland for milling, where it was cut down to size and checked for quality.

The remaining timber requirements were made up from Irish forests, with this actually turning out to be the lowest-carbon timber by virtue of only being shipped across the Irish Sea once.

Dr French points out that there is no English mill close enough for it to be cost-effective to mill the timber here, hence the need to go to Ireland, but that Adapt is now looking into the possibility of establishing one close to Thetford forest in future.

“There was no waste, either – anything that was left over from machining was used by a local Irish fencing contractor,” he says.

Thatching for victory

As well as the timber, a number of other sustainability innovations have been included in the building to achieve the exacting green ratings.

The most immediately obvious and striking element is the thatched roof and walls.

The roof above the south wing is being covered by master thatcher Stephen Letch, with the western elevation home to alternate panels of thatching and glazing all the way along.

“Stephen has a team working with thatching the roof in-situ – the thatched portions on the facade will be manufactured offsite,” Mr Brock says.

“All of the reed used here comes from local sources – a lot of reed used in thatching elsewhere comes from Europe nowadays.”

“Wen we excavated the lecture theatre we found a cluster of them. That’s extremely rare and our geologist hadn’t seen anything like that before”

Steve Brock, Morgan Sindall

Sitting alongside the thatching on the roof, juxtaposing old and new building technologies, are 160 solar panels covering 450 sq m in total on the west, south and north sides of the building.

Also on the roof is a rainwater harvesting system. “The rainwater is collected in large flat gutters and flows into catchment areas,” Mr Brock explains.

“This has two outlets to feed the tanks inside, so as long as you have fairly regular rain you’ll have a supply of water to the toilets. There’s another outlet too to cope with a one-in-100-year storm.”

Other sustainable initiatives used include triple-glazed windows, passive ventilation, a cross-laminated timber lift shaft, bio-renewable cladding on internal meeting ‘pods’ and recycling of timber and concrete from other projects.

Sinking feeling

All has not been completely smooth sailing so far, though, with the team meeting some significant challenges along the way.

In particular, they encountered some difficult ground conditions early on in the project.

“During the site survey we found a disillusion feature, or a sink hole,” Mr Brock says. “That was designed in so we put a cap over that.

“Then when we excavated the lecture theatre we found a cluster of them. That’s extremely rare and our geologist hadn’t seen anything like that before.

“The concrete slab in the theatre is designed to span a 3 m disillusion feature, but nobody anticipated a cluster.

“We couldn’t continue so there was a four-week delay. The client was very understanding – we dealt with it swiftly, but it did delay the groundworks.”

Innovations

Passivhaus and BREEAM Outstanding standards on track

Thatched roof and external walling

98% recycled steel frame

8% GBBS used as cement replacement

58 tonnes of recycled newspapers for insulation

Timber sourced locally from Thetford forest


The design called for the south wing of the timber frame to be built first, before the link and lecture theatre were constructed to provide staibility, with the north wing going in last with a flying canopy.

Given the geology the team had discovered, however, they realised it was impossible to site the crane outside of the lecture theatre as it seemed probable that more sink holes would be discovered.

“This would introduce more costs, more concrete and more carbon, as well as more delays, so we decided to sit the crane within the lecture theatre footprint,” Mr Brock says. “We cast the concrete for the lecture theatre basement and sat the crane in there.

“We found the results were very similar to normal concrete and the horror stories were nonsense – we had good results”

Steve Brock, Morgan Sindall

“It worked really well but it meant we couldn’t put the theatre in at the same time as the link, which introduced a lot of temporary bracing during construction.”

The concrete itself was more sustainable than normal, with 70 per cent ground granulated blast furnace mix (GBBS) used as a cement replacement for the foundations and structure – reducing the embodied carbon by 30 per cent compared with a normal building of this size.

“We weren’t familiar with that ratio of cement and had heard some horror stories,” Mr Brock says. “But we found the results were very similar to normal concrete and the stories were nonsense – we had good results.”

Sustainable learning

It’s clear that a great deal of thought has gone into making the Enterprise Centre as sustainable as possible, with every product and technique undergoing careful consideration to make sure it as green as it could be.

Satisfying the demands of both Passivhaus and BREEAM has proved a particular challenge, though.

“Every decision we take requires a lot of discussion,” Mr Brock says. “One product might fit Passivhaus beautifully but doesn’t really sit well with BREEAM and is awful for embodied carbon, and likewise the other way round. That bit is tough.”

“We won’t come to the end of that learning curve for a long time”

Steve Brock, Morgan Sindall

Mr Brock acknowledges that the client is really “driving the agenda” forward on the scheme and that he has contact with Dr French “very regularly”. “That is a bit alien to me but it’s working well,” he says.

This pushing of the boundaries of what can be done with a commercial building, ensuring it will have very low energy consumption and embodied carbon while being built in the most sustainable way possible, has challenged the Morgan Sindall team.

“Every day of the week there is something new happening,” Mr Brock says. “I had no previous experience of Passivhaus or anything like that and I’m not particularly clever or practical, but I’m learning something new all the time.

“We won’t come to the end of that learning curve for a long time.”

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