St Mary Redcliffe Project 450 RIBA 2 Stage End Report

In some public areas low surface temperature (LST) radiators have been required where particularly young children could
be at risk from scalding by conventional radiators. Consideration should be given to
the use of some areas so see if venerable adults or young children are regularly using
the space. Shapes, sizes and styles for LST radiators are more limited. Finishes for all
radiators are generally white but can be coloured as necessary.
All radiators would be fitted with thermostatic valves for local control.
Radiators sizing will need to take into account the lower water temperatures expected
to be generated by the air source heat pump and will therefore be “oversized” to
achieve the same output as from a traditional gas fired boiler system.
Existing Heating Plant
The existing boiler plant serving the church is to be retained as there are no reports of issues with this system.
The current architectural layouts currently require the slab above this plant room to be lowered. From site inspection,
this will likely affect the distribution pipework that leaves the plant room at high level. A survey will need to be conducted
to make recommendations regarding the required diversions.
Heating Distribution
LTHW and refrigerant distribution pipework will be distributed largely within ceiling voids and vertically via dedicated
risers. Pipework will all be insulated to mitigate the risk of overheating.
9.2 Cooling
Where possible, cooling is not proposed for the new development. Natural ventilation solutions will instead provide
outdoor air to mitigate the risk of overheating.
These will be thermally modelled at stage 3 to inform the expected conditions in the space and any limitations that this
puts on the use and occupancy of the spaces.
At this stage the expected exception to this is the events space due to its high occupancy and glazing. 2No. options to
provide the cooling to this space are being considered as described below:
Air Source Heat Pumps – VRF – As described in the heating section above the external heat pumps and FCUs are able to
provide both heating and cooling
Packaged Air Handling Plant Providing Cooling – Areas with high air volumes can be heated and cooled by heating the
fresh air supply. This is a potential solution for the events space and the Hogarth Gallery. As these spaces have fairly high
occupancy, this drives a high supply air volume requirement, which has the capacity to provide cooling.
A packaged AHU will use a refrigerant compression and expansion system to take heat from exhaust air and “reject” this
into the supply air stream. A thermal wheel will also be used to recover heat from the extracted air.
This option reduces the required external plant in instances where high air volumes are already required.
9.3 Domestic Water Services
Cold Water
The proposed extension will increase the domestic cold-water demand of the site. It is therefore expected that an upgrade
to the mains cold water will be required to serve the existing and new water outlets.
No cold-water storage has been identified on site, and so it is assumed to be a mains fed system. Therefore, it is reasonable
to assume that sufficient pressure is available and can a mains fed system can be extended to serve the new development.
Confirmation of the cold-water requirements of the kitchen is required.
Hot Water
Due to the distributed nature of the WCs and kitchen facilities, local hot-water provision is
preferred.
Each remotes WC area will be provided with a direct un-vented water heater to provide hot
water to the basin outlets. The heater will be located under sinks or concealed in risers/store
rooms as required.
Due to the limited size of the proposed kitchen, it is not anticipated that this will have a high hot
water demand and will therefore also be suited to local electric hot water production, but in this
case with a small amount of storage.
The hot water requirements of the kitchen are to be confirmed.
9.4 Ventilation
A successful ventilation strategy is essential to ensure there is adequate fresh air in all areas within the building and that
a comfortable temperature is maintained in Summer.
All areas and rooms such as gallery, exhibition spaces, event spaces and kitchens etc should be adequately ventilated so
they are fit for purpose.
The proposed strategy, in keeping with the passive design approach, is to provide natural ventilation for overheating and
fresh air to as much of the new development as possible.
Where necessary, mechanical ventilation shall be provided. The AHUs (Air Handling Unit) providing the mechanical
ventilation need to have high efficiency heat recovery and be designed such that the ductwork pressure drop is minimised
to reduce the associated energy consumption.
Exhibition Spaces, Café & Education Space
1563.R1 – Stage 2 report Page 16 of 29