Eco-Exhibition Centre completed at Longstanton

Rees Pryer Architects have just completed an exemplary exhibition centre on the new Cambridge Guided Busway route at Longstanton. The building showcases low carbon living and uses an innovative pre-cast hemcrete construction system along with various low carbon technologies to not only house an exhibit and learning resource, but to be an exhibit in its own right. 

The Client, Cambridgeshire County Council, wanted a focal point for the new transport hub at Longstanton which will ultimately serve the proposed eco-town of Northstowe. The brief therefore was to provide a building that not only demonstrates what is to be expected of these low carbon properties, but shows visitors ways in which they can improve their own environmental credentials and understand how the various systems work. The building also doubles as a waiting room for the Busway and provides office space for staff as well as facilities for visitors and bus passengers. 

The design concept was simple – a series of ‘pods’ housing the main functional elements of the building, the space between becoming the exhibition space. All of the components are connected by an oversailing green roof that also creates a protective colonnade leading to the bus embarkation points. 

One of the most innovative aspects of the project is the pioneering use of Lime Technologies’ Hembuild system. Using a glulam timber frame, the main superstructure of the building consists of a series of factory-made, pre-dried hemcrete panels. These timber framed panels are packed with a mix of hemp and lime-based binder in controlled conditions to create a carbon-negative building product, complete with breather membranes and vapour control layer. This brand new system provides a whole envelope solution to create an air-tight shell ready for following trades to commence straight away. This not only reduces site time but takes away the issues of weather affecting the installation and curing of hemcrete. The system was chosen ahead of “traditional” timber frame as it also provides the advantages of thermal mass and excellent u-values, stabilising the seasonal temperature swings and thus reducing energy demand. 

As a result the scheme has reduced heating requirements which are met using a ground source heat pump with radial probes centred at a manifold in a glass topped “well” in the exhibition space. The heat pump itself is located in the glass fronted plant room, which along with the thermal store, photovoltaic inverter, and monitoring equipment form an interactive display for visitors. Almost all of the electrical demand for the building is met by the photovoltaic array along the southern edge of the green roof, the panels also acting as a brise soleil to the exhibition space. The building also includes an assisted natural ventilation system with heat recovery. 

The project is on target to achieve a BREEAM “Excellent” rating. It is hoped that the scheme, which was delivered to a tight budget, can act as a template for other projects including school and commercial buildings. 

The project team included:- 

SEH French Ltd – main contractor – www.sehfrench.co.uk

MLM Consulting Engineers – www.mlm.uk.com

SEH Commercial – renewable technologies – www.sehcommercial.co.uk

Lime Technologies developed the Hembuild construction system – www.limetechnologies.co.uk 

Other key suppliers:- 

Bauder – green roof

Econic – ground source heating

Sylvagroup Ltd – timber frame

Breathing Building Ltd – E-stack ventilation systems