Bartholomew Barn is the first Saint-Gobain Multi Comfort building to be completed in the UK, taking into account occupants’ health and wellbeing, in addition to excellent environmental credentials.
The King’s School, Worcester required a new multi-purpose hall for sports, assemblies, drama, music and dance for their Junior School, King’s Hawford.
The new hall needed to be sympathetic to the character of the existing buildings at King’s Hawford. The building needed to fit with the rural vernacular of the area, which has a rich tradition of barn-style, timber-framed buildings.
The Multi Comfort design concept is about building and renovating our homes, offices, school, hospitals and other buildings in a way that gives us improved comfort, health and wellbeing while protecting the environment. Saint-Gobain has created a full set of design criteria that are achievable both individually and can work together to provide optimum user comfort. The Multi Comfort concept recognises the interrelation between four key design elements – thermal comfort, acoustic comfort, indoor air comfort, and visual comfort. The concept also recognises that buildings need to be designed and procured in a cost-effective way to give value, not only to the building user but to the client.
By taking a holistic approach to building and design, the aim of the Bartholomew Barn project was to demonstrate the interrelation between these design elements, and the wellbeing benefits a whole-building approach could have on building occupants.
Use of timber
Timber was a central part of the construction, as Bartholomew Barn was conceived as a contemporary architectural version of a traditional cruck frame barn. The glulam structure was chosen as a modern equivalent, and provided structural spanning capabilities in a simple portal structure. This enabled the overall wall to be thinner than standard masonry or other wall solutions.
In addition, timber is the ultimate material in sustainable design, sequestrating rather than adding to global CO2 emissions, and with full supply chain and chain of custody to PEFC or FSC principles, ensured it was from a truly sustainable source.
Timber was also used in the Barn to enhance the acoustic performance of the building, using similar design principles of concert halls to improve speech intelligibility.
Ideal internal air comfort
Under the Saint-Gobain Multi Comfort standard, it is important to look at the thermal comfort of building occupants. British and European standards and basic building physics teaches us that if internal air flow movement can be controlled to below 0.8m/s we can reduce the perception of feeling cold and therefore reduce the urge to turn up the thermostat. Increasing the temperature by just 1oc can increase energy costs by around 10%.
In addition, if the fabric can be designed with low geometrical thermal bridge factors (PSI values), as well as a good U-values, we can improve the internal surface temperatures to above 16oc. The maximum temperature in a Multi-Comfort building is 20oc, so there is a maximum of 4oc between the air temperature and surface temperature. Under ISO 7730 and EN 15251, if the surface temperature is within 4oc of the air temperature, only 6% of building occupants would be dissatisfied with this internal environment, unlike most buildings today where dissatisfaction levels can be as high as 50%.
These two key factors result in significantly lower running costs – initial estimates suggest they’ll be lower than £400 per year. This was only possible using such insulated construction (0.15 U-value and lower).
The design has optimised the heat gains from south-facing glazing to enable a good energy balance between heat loss and gains, whilst reducing the potential for overheating in peak summer periods. Large windows along the length of the external walkway maximise the amount of north light admitted into the building.
Rooflights in the changing room areas admit an appropriate level of daylight without compromising privacy. Additional rooflights and windows above doors assist with natural ventilation and natural light, avoiding both unwanted heat gains and glare, which is detrimental for sports use.
Other sustainability measures included low flow water fittings and cisterns, full recycling facilities, compliance with the Considerate Constructors Scheme site management guidelines, and responsible sourcing of low embodied energy building materials.
The Bartholomew Barn is designed and certified to the Passivhaus standard and is also certified to Multi-comfort standard. This guarantees excellent thermal insulation standards, exceptional airtightness and filtered heat-recovery ventilation.
This building has created huge potential for raising awareness of modern building technology and climate change issues among the School community, for incorporation into the school curriculum. The building’s heat loss, renewable energy levels, temperatures, comfort levels etc. are being monitored and compared with other older buildings elsewhere in the school.
Find out more about the project and what architects and occupants have to say.
Download the full Multicomfort case study and analysis here.