Every little helps
A Dimplex ground source heat pump is being used to supply domestic hot water to the first supermarket built to PassivHaus standards in the UK and Ireland, a Tesco store in Tramore, County Waterford.
PassivHaus buildings are designed to be extremely energy efficient – usually this means the annual energy consumption is under 15kWh/sq m. The building fabric features high levels of air tightness and insulation to keep heat in, meaning only minimal space heating is required – and making the water heating an even more important consideration in the performance of the building.
The building’s hot water is provided by a heat pump system jointly designed by Dimplex and Dynamic Energy Solutions and installed by County Kildare-based Geothermal Solar. The system takes an unusual approach to meeting the store’s requirements; it uses a Dimplex SI 11 MEH ground source heat pump to draw heat directly from the water used in the building’s cooling system, efficiently recycling the waste heat from the chiller cabinets on the shop floor. The heat pump easily meets the total hot water requirement for the store, including the staff canteen and washrooms, and the customer washrooms.
Fergal McEntee of Dynamic explains: “We could have used a water source heat pump instead. However, a water source installation can be technically more complex, while the closed loop Dimplex ground source unit allows us great flexibility in the system design. Plus, we wanted to take advantage of the higher flow temperature that this unit gives – it’s ideal for meeting the supermarket’s hot water requirements.”
The Dimplex high temperature ground source heat pump can deliver flow temperatures of up to 70ºC. At Tramore, where typical intake temperatures from the cooling system are around 25 – 28ºC, the heat pump easily produces flow temperatures of 60 – 65ºC – and a CoP of around 4.0 is typical under these quite unique conditions.
More fresh thinking was demonstrated in the delivery of the heat pump system. In an approach that ticks all the boxes for modern methods of construction, minimising time spent on site and associated costs, a complete plantroom containing the heat pump was pre-assembled in the UK and shipped to Ireland, to be attached to the side of the supermarket building.
However, this method also presented the designers with an additional challenge to work around when it came to the sizing of the pipework, as it had to be able to accommodate all the adjustments to the system which may have been required to adjust performance once the heat pump was installed.
Fergal McEntee continues: “This application looks at the energy requirements for supermarkets and has opened the business community’s eyes to the possibilities for heat pumps, particularly with regard to using them to provide hot water. As a result of this installation, we are now talking to commercial clients in a wide variety of sectors.”
The supermarket incorporates a wide variety of other environmentally-friendly initiatives, including PV panels, a wind turbine, rainwater harvesting and infiltration permeable paving in the car park, the use of natural refrigerant gases in cooling systems, triple glazing throughout for insulation and roof-lights to allow use of natural daylight where possible.