The office of The Marble & Granite Centre, situated between the lake and the canal in the green belt of Rickmansworth, north-west of London, is both small and perfectly formed.
Self-sufficient when it comes to energy use and unyielding when it comes to energy loss, the building is disguised in the landscape to the point that, from the yacht club on the lake behind it, it is barely visible at all.
This is because it is built into the ground, submerged on three sides by earth, leaving the front glass facade visible from the entrance, but only the mono pitch green roof, which protrudes just over the surface of the ground visible from the rear.
Because of the green belt, the council were adverse to any new buildings going up – hence these offices use the exact footprint of the cement-batching plant that was located here previously. The centre was up and running from three portacabins while planning permission was still in process.
“It was a perfect piece of land to utilise,” explains Mark Fairhurst, managing director of Mark Fairhurst Architecture + Design, and head architect on the project.
“It was a building refuse site, having been a cement-batching plant; it is a brownfield site in a greenfield context.”
Because the proposed office was related to the use of the site, the council were more amenable to the project going ahead, and consent was eventually granted.
The space needed for the building was already cut out of the earth, “although we did have to insert a new steel structure to place the office in,” admits Fairhurst.
“We were restricted from going any deeper because the foundations were already at water level,” he explains, hence the waterproofing; a drain cavity ensures that any water that comes in is immediately pumped back out again.
Fortunately the site offered up an interesting space to work with, but there was the lack of a main gas supply to contend with – a challenge that took Fairhurst and his client to Ireland, to learn about the virtues of geothermal heating.
“It’s a practice that is already well used in countries, such as Germany, that have never benefited from the privilege of cheap oil prices,” Fairhurst states. “These countries are more incentivised to look into, and invest in alternative energy sources. At the outset of the project, the advantages that geothermal heating has to offer the UK were not as prominent as they are today.”
The geothermal heating employed for this four-storey build takes the form of three 100m-deep boreholes in the ground, through which water is pumped.
The ambient temperature underground is around ten degrees; the water heats to this temperature and is then pumped back up the pipes and compressed, a process which raises the temperature by another ten degrees, enough to circulate through the building and provide underfloor heating.
Another process that contributes to the building’s predicted excellent BREEAM rating is the heat-exchange technique used to ventilate the building. In a heat recovery system, air is circulated round the building, but not conditioned.
Because the build is north-facing, the large expanse of glazing at the front does not cause excessive heat gain, while the south side of the building is fully insulated, reducing heat loss further.
A skylight over the lift and stairwell at the back of the offices ensures that areas not reached through the glass front of the building are also exposed to natural daylight.
The green-tinted glass which fronts the building, as well as reflecting the trees that surround it, creates a polished surface that reflects the polished slabs of marble granite that stand aligned in the Centre’s large foreyard.
The Marble & Granite Centre, a leading importer and distributor of natural stones in the UK, deals with material from as far afield as Italy, France, Spain, Scandinavia, South America, China and Africa. Retailers and manufacturers come in to specify materials for anything from building cladding, kitchen surfaces and bathroom floors to retail floors.
The build itself makes use of natural stone through a base layer of black granite in the front facade, and marble floors, stairs and work surfaces. The building is clad in western red cedar timber, completing the natural integration of the building to its setting.
“Marble is an interesting material to work with,” explains Fairhurst, who is now determined to get some of the more unusual samples at the centre into future projects, “perhaps a bar surface or bespoke reception,” he muses.
The other advantage of the site for the owner of the business is to do with his interest in repairing and restoring canal boats and historic wooden narrow boats, something he does for different charities. An old barge narrow boat, mid-repair, sits adjacent to the site on the canal.
“It was always going to be a subtle build, sympathetic to the landscape,” Fairhurst explains. “Despite all the technical complexities of building a small office underground, the planners liked the approach.”
Had it been a domestic build, more could have been made of the ability to walk out of the top floor and onto a hilltop overlooking the lake, but, with a staff of around 20 based in the office, it definitely remains a logistical business operation, not a show apartment.