New Brewery Arts have a building in their complex which was converted into a theatre in the 1980’s, but whose use was declining, it was proposed to the trustees that the Centre would be more financially sustainable if the theatre were converted into a Youth Hostel, for which there is an identified need in Cirencester, which had the ability to house a party of school children but also provide accommodation for those attending courses and workshops run by New Brewery Arts. We were appointed architects for this hostel with up to 48 bedspaces in October 2013 in competition with 2 other firms of architects with established track record of designing Youth Hostels. From the very beginning we proposed that the youth hostel be designed to meet the Passivhaus “Enerphit” standard, a very low energy standard achieved through following a rigorous design process monitored on a suite of spreadsheets. New Brewery Arts was established in Cirencester in 1989 from the merger of Cirencester Workshops and the Niccol Centre. Their site at a former brewery building receives around 100,000 visitors a year. The business is a registered charity and employs 32 people locally. The Barrel Store Youth Hostel building will add an additional revenue stream for the charity and protect the long-term viability of the project. Speaking of the project Ali Russell, Centre Director for New Brewery Arts says “I originally pitched the idea of the Youth Hostel to the Trustees as a way of creating a sustainable future. It has been funded mainly through grants from The Arts Council and Winstone Trust, as well as through private donations. We’re really excited to see the project come to fruition and know that it will be a great addition to Cirencester and the County. The Passivhaus status will be a bonus and hopefully the success of our project will be a pilot for more projects like this in the future.” The Barrel Store will be the UK’s first ever Passivhaus Certified Youth Hostel (the only internationally recognised, performance-based energy standard in construction) and also the largest building in Gloucestershire with this certification. When completed in Spring 2016, the new hostel will accommodate visitors to the area and those attending courses and workshops run by New Brewery Arts. The formal definition of a Passivhaus is “a building in which thermal comfort can be provided solely by heating or cooling of the fresh air flow which is required for good indoor air quality”. The “haus” in german means building, so that the criteria can be applied to schools, offices etc as well as houses. In practice this means: 1. A building with space heating requirement designed close the theoretical minimum 2. Using Passive principles to their full extent before active – i.e. insulation before heating system 3. Low energy design in all the services including lighting and appliances The emphasis is as much on comfort as minimum energy consumption. The standard was designed by a german physicist, Wolfgang Feist, who devised a very comprehensive series of linked spreadsheets which allows pretty much all aspects of the design to be analysed in great detail to allow the performance to be accurately predicted. This is then accompanied by extremely careful quality control monitoring and testing of the actual construction to ensure that the predicted performances are achieved (this has been a failing on many so called low energy buildings) In terms of performance the following criteria need to be met: 1. Air tightness – Max 0.6 air changes per hour when tested at 50 Pascals (Comfort and Energy) 2. Surface temperature – No surfaces less than 17 degrees c (the design air temperature is 20 degrees, assuming still air within the house). If surfaces are more than 4 degrees lower than air temperatures, a room will feel uncomfortable. The main implication of this is that windows need to be triple glazed (Comfort) 3. Summer Overheating – For no more than 10% of a year can internal temperatures be greater than 25 degrees (although we were advised to aim for 5%). This may require shading of south facing windows and louvers on east and west facing windows (Comfort) 4. Ventilation – 30m3/hr.person (Comfort) 5. Heating & Cooling Load – Max 15kWh/m2yr @ 20 degrees C or 10W/m2 (Energy) 6. Primary Energy (Main supplies into house) – Max 120kWh/m2yr (Energy) In practice this means: 1. Compact Building Forms 2. Simple glazing configurations 3. U values to walls, floors & roofs less than 0.15W/m2k 4. Triple glazing to external joinery with an average u value less than 0.8W/mk 5. Whole house heat recovery ventilation systems 6. A carefully considered and implemented air tightness strategy 7. Use of low energy lighting and appliances The Enerphit standard is a slightly more relaxed standard for the upgrading and conversion of existing buildings. It recognizes the difficulties of achieving the full Passivhaus standard when working with existing structures, primarily due to the difficulty of removing thermal bridges. For instance the heating and cooling load is allowed to increase to a maximum of 25kWh/m2yr @ 20 degrees C. . The Youth Hostel will be certified under the Enerphit scheme The Barrel Store design has presented a few challenges compared to other Passivhaus structures, simply because of the scale of the project and the number of rooms requiring water supply and ventilation. The particularly challenging aspects of this project have been the design of the wall and roof insulation. Budgetary constraints at the design stage meant a wholesale replacement of the roof would not be possible, and the new, thicker insulation had to be fitted internally, complicated by the need to upgrade some of the structural timbers. The wall insulation system will achieve a U-value of around 0.2 W/m2.K, the roof and floors achieve around 0.1 W/m2.K, and windows at 1.0 W/m2.K (centre pane 0.52 W/m2.K). The ventilation system will recover 80% of the heat from the stale exhaust air into the fresh supply air.” The project is being constructed by DJP Construction from Cheltenham, who have a reputation for building to a very high quality but are new to Passivhaus Standards. David Gilkes and his team have working closely with the Project Manager and design team to understand the principles of Passivhaus buildings and the constructional challenges ahead. Technical details for the Youth Hostel build include: • 44 bedspaces 14 rooms • It has been developed in close consultation with the YHA and includes maximum privacy for shared accommodation rooms and minimal sound transmission between bedrooms. • The internal layout is of a generous entrance hall with a top lit winding oak staircase lined with ash boarding (the barrel…) with a Community Room and kitchen to one side at ground floor level, and to the other laundry, linen store, accessible bedroom and shower room and other bedrooms with 30 bedspaces at first floor level • It will adopt the Passivhaus principles of high levels of insulation, air tightness and controlled ventilation using mechanical ventilation systems with heat recovery. The building also features a “microbore” hot water supply pipework to minimise heat loss from the hot water system. • Minimal sound transmission between bedrooms thanks to consultation with Ion Acoustics • The proportion of rooms requiring water supply and ventilation was very high and this resulted in a more complex servicing installation than is normally found in Passive House projects • The construction will be within the existing envelope of the stone building with slate roof; a highly insulated and air tight timber structure will be inserted with accommodation at ground and first floor levels and the Plant in the roof void • The external walls are being insulated from the inside with a build-up of wood fibre insulation products, which allow the building to “breathe” and thus reduce the possibility of the build-up of water vapour and condensation. At the design stage, the existing roof coverings were planned to be retained, with rigid insulation boards being applied between and under the existing rafters to meet the required levels. (In fact the roof coverings have been replaced, as once opening work took place, it was discovered that the slates had previously been used twice and could not be further re-used). The existing lower ground floor is being filled and the new ground floor slab will “float” on a thicklayer of insulation board which will be turned up at the edge of the perimeter of the slab to remove “cold bridges”. • The finishes use natural finishes where the budget permits – Hardwood (a mixture of oak and ash) and linoleum flooring, and waxed or stained timber internal joinery