Building Services Engineering
sense occupancy, and these will be linked to dampers that will open automatically via the BMS to activate mechanical fans. In the ‘staff only’ areas where there is no safety or tamper risk, Steven A Hunt & Associates has also designed heat recovery units into the specification to aid energy efficiency.
An artist’s impression of the entrance to the £14 million Ancora House. Construction of the Tier 4 facility began on site last April, and is scheduled for completion this September.
installation that would maintain the highest levels of safety and security for patients, staff, and visitors, while delivering a low carbon, energy-efficient building in line with the Trust’s environmental goals and best value operational cost objectives.
CONCEALED SERVICES Central to the safety and security element of the building services strategy was the need to ensure that there was no exposed services infrastructure in any of the patient areas, and that anti-ligature fittings were used throughout. It was essential to interrogate the risk of
every aspect of the building services design, because normal safety rules do not apply in an environment where patients may be quite determined to cause themselves physical harm, and very creative in the ways they go about doing it. As a result, the services wiring and pipework have not only been designed to be hidden from view, but are also inaccessible to patients, and all electrical fittings have been specified with specialist anti-ligature designs. To overcome the ligature risk of conventional
radiators, Steven A Hunt & Associates has specified underfloor heating throughout the unit, with the required pipework embedded in the screed. While a dummy temperature control unit is recessed into the wall for each patient area to give the patients an impression of controllability over heating and cooling, the heating system will, in fact, be controlled centrally by a building management system (BMS) that integrates all mechanical and electrical controls for the entire facility.
INDIVIDUAL TEMPERATURE CONTROL This does not mean, however, that the temperature of each area cannot be modified to suit the needs of each patient room. The facility has been designed with a services cupboard accessible only by staff from outside the room, where individual temperature controllers will be located. Often patients in this kind of environment are very sensitive to temperature, and an environment that is too hot or too cold can have a significant impact on their behaviour and sense of wellbeing.
2 2 THE NE TWORK J u l y 2 0 1 6 The heating system has been designed to
offer a constant and comfortable ambient temperature, with a reverse cycle cooling facility for the summer months. Underfloor heating is an ideal way to maintain a consistent temperature across the entire building, linked to temperature sensors within the BMS.
EFFICIENT HEATING AND COOLING The underfloor heating also provides the ideal solution for energy-efficient heating throughout the facility, and Steven A Hunt & Associates has designed the system to operate using an air source heat pump as the main energy source for both heating and cooling. The lower temperatures generated by the heat pump are ideal for underfloor heating installations, and the heat pump runs constantly day and night, and all year round, to ensure a consistent energy feed into the heating and cooling system. Steven A Hunt & Associates has designed
the system as an N+1 configuration, with a duty air source heat pump plus a standby as a back-up should the duty heat pump fail or require maintenance. The BMS will be programmed to switch the energy source to the standby heat pump should it be required, removing the risk of heating or cooling failure. In addition to the air source heat pump,
Steven A Hunt & Associates has also included a 10.1 kW solar PV installation in the specification for the CAMHS unit. This will contribute to the energy load for the facility, and also provide the Trust with a higher Feed-in Tariff (FIT) return, contributing to the unit’s operational cost efficiency.
BMS WITH MANUAL OVERRIDE With no window opening for ventilation in the patient areas for safety and security reasons, Steven A Hunt & Associates also had to devise an energy-efficient approach to ventilation for the CAMHS facility. Once again, this will be controlled by the BMS system, with manual over-ride available to members of staff in each patient room’s service cupboard. The facility will be maintained at constant pressure, with extract systems set to a constant trickle rate 365 days/year. PIR sensors will be installed to
CUSTOMISED CHP Like any inpatient healthcare environment, the CAMHS unit is expected to have a high demand for hot water. Incorporating the energy demand for this into a low carbon plan for the building has also formed a key part of the energy source strategy for Steven A Hunt & Associates. The company has included a
small CHP (combined heat and power) unit in the specification, which has been designed specifically to meet the anticipated DHW (Domestic Hot Water) demand for the facility. Often CHP units are put in that are much
too big for the actual energy demand on site, which means they generate too much energy, some of which is wasted. For the CAMHS unit in Chester we have used computer modelling to estimate the hot water demand, and designed the CHP to provide 20 kW of thermal load for use in the hot water system. The CHP will also provide an additional 5 kW of electrical load, which will contribute to the building’s power requirements.
LOW ENERGY LIGHTING The lighting installation has also been designed to use as little energy as possible, with LED lighting throughout the building. The units not only offer low running costs but, with an average service life of 50,000 hours, also ensure a low maintenance solution which contributes to the operational efficiency of the building, and will minimise disruption for patients. A lighting control system incorporated into
the BMS controls the lighting via a combination of presence and absence detectors and daylight sensors. There are no light switches in the patient bedrooms, and the fittings specified are a combination of surface-mounted anti-ligature units and recessed lighting. Anti-ligature strip lights have been specified for the corridor areas. The lighting specification is an area that can
impact on the building’s efficiency, patient safety, and patient wellbeing, so it was important to draw up a very detailed specification.
‘Incorporating the energy demand for this into a low carbon plan for the building has also formed a key part of the energy source strategy’
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