Cressex Community School

 

The case study on Cressex Community School highlights some of the issues when a school is only half occupied after handover and the facilities manager is not appointed until well after that date.    

Project Lead
Jesse Putzel, BAM Construct UK Ltd

Building type, sector and stage
Non-domestic, new build, school, post construction, in-use, South East, High Wycombe

Keywords
School, BMS, mechanical ventilation, GSHP, Biomass,  

Summary
Cressex Community School is a secondary school in High Wycombe, Buckinghamshire. The 3 storey building of 11,600m2 usable floor space was built as part of the One School Pathfinder Programme within Building Schools for the Future. The building was designed to meet a 60% reduction in CO2 over 2002 building regulations, which was met via a combination of efficient building fabric and renewable systems. The school has capacity for 1500 pupils but has been under occupied with approximately 500 pupils being present for the first 2 years of occupancy. The new building replaced the old school which included a number of small buildings spread out over the site.

The new school has a compact design with three teaching wings radiating from a central ETFE covered courtyard connected to a fourth block for sports, administration and other applications. The building is fully mechanically ventilated via large air handling units with thermal wheel heat recovery located on the roof.  Heat is provided by a combination of a gas boiler, biomass wood chip boiler and ground source heat pumps (GSHP).  The borehole GSHP also acts to provide an element of precooling during the summer months.  The building services are controlled by a sophisticated BMS and metering package. While the new building offers a welcome improvement to teaching facilities, it is also highly complex in comparison to the old school, leading to steep learning curves for those involved in running it.
The building achieved a BREEAM ‘Very Good' rating, and a B rated EPC and began occupation in September 2010.  This study analyses how the school performs in reality, and investigates the potential for further improvements.

Energy Use
Initial Simple TM22 analysis of the school suggests that Cressex performs significantly better than the TM46 benchmark which represents average data for all ages of schools. The benchmark data has much higher fossil fuel usage but significantly lower electricity usage. In contrast, the school performs very similarly to the benchmark data used by Carbon Buzz. This data is from recently built schools and is therefore a more useful benchmark.  While the building appears to perform well, it is not currently meeting its full potential and the aim of this study is to find why this is the case and to investigate ways of improving this.

Key Performance Indicators
Project cost: £25.9 million
Floor area: 11,600m2
Building regs estimate of CO2: 14.7 kgCO2/m2.yr
BREEAM rating: Very Good
EPC rating: B (31)
DEC: not assessed