Our work to combat climate change at Wimpole Estate

Row of solar panels at Wimpole Estate, Cambridgeshire — Row of solar panels at Wimpole Estate | © National Trust/Catherine Hayburn

As part of the National Trust's Renewable Energy Investment Programme, Wimpole has reduced its dependence on fossil fuels in recent years. Here is what Wimpole has been doing to combat climate change on the estate.

What has changed?

We've removed our oil-fired heating and hot water system for the hall and restaurant and in their place, we've installed a ground source heat pump using boreholes in part of the current car park and new heat converters. With the removal of this oil-fired system, not only should it reduce the cost of buying all the oil, we will also reduce our carbon emissions.

We've also installed a Solar Photovoltaic Panels in the same location as the new car park, which will use solar power for electricity in the new visitor welcome building and we'll sell some of the power generated back to the national grid.

The new visitor welcome building is also heated by renewable energy, this time an air source heat pump, supplemented by a wood burner in the colder weather, burning Wimpole timber.

The Wimpole estate also has a sustainable drainage system so the runoff water from the estate’s visitor car park actually drains through a series of ditches and swales and into ponds. That water is naturally filtered and the silt removed. And that water can then be returned to nature without using extra carbon.

The visitor welcome centre at Wimpole Estate, Cambridgeshire — The new visitor welcome centre at Wimpole Estate | © National Trust Images/Catherine Hayburn

Ground source heat pump at Wimpole

Our Ground Source heat pump was the first phase of our renewable energy project, providing greener heating in the restaurant and mansion and allowing us to remove our oil-fired boiler.

Why have we installed a ground source heat pump at Wimpole?

Between them, Wimpole Hall and the Old Rectory Restaurant consumed around 35,000 litres of oil each year. Switching to a ground source heat pump system removed the risk of an environmentally damaging oil leak and reduced the cost of buying all the oil. It will also reduce our carbon emissions.

The system uses around one third of the energy used by the oil boilers, reduces carbon emissions by 47 tonnes per year and will save over £8,000 a year in fuel costs. The low temperature background heat provided by heat pumps is better for sensitive collections at our properties like Wimpole rather than the fluctuating high temperature heat from a fossil fuel boiler.

'This project is helping us to show that even in the most historically significant locations, it is possible to move away from fossil fuels and switch to low carbon renewable energy sources without negatively impacting on the places we are caring for.'

- Dee Nunn, Project Manager

How does a heat pump work?

A heat pump is a device that uses a small amount of energy, in the form of electricity, to move heat from one location (the ground, the air or water) to another (eg. a building). At Wimpole, the pipework is installed in boreholes in the ground (up to 150m deep). The heat is then amplified with compressors and passed through something called a heat exchanger - basically a fridge in reverse. From there it’s taken to an underfloor or radiator heating system.

What does it look like?

Now it is installed, you can only see three manhole covers in the ground, which will be in the restored parkland once the car park is removed. These will allow access to the chambers where the pipework is joined together, other than that you can see little evidence of the system.

The plant rooms have slightly different kit in them compared to the oil-fired system but are maintained as any system would be with weekly, monthly and annual checks.

Wimpole's Solar PV Project

Our solar photovoltaic (PV) installation was the second phase of the renewable energy project at Wimpole, providing electricity for the new visitor welcome building and helping us to ‘grow our own’ energy from the sun.

When the the new car park and visitor welcome building was constructed in 2019, solar photovoltaic panels were installed in a discrete location in the corner of the new car park.

This is currently the biggest solar installation in the National Trust, eight times larger than the largest Trust solar installation to date. They will generate around 350,000kWh of electricity per year – enough to meet the electricity needs of 113 average UK homes or around half of the electricity used across the whole Wimpole Estate.

How do solar panels work?

The panels are positioned to maximise the harvesting of the sun’s rays throughout the day. A bank of inverters converts the suns power into electricity that the estate can use. As solar panels continue to work even on a cloudy day, this system is generating electricity for the Wimpole Estate 365 days a year.

The electricity is fed back via cables to the utility building next to the visitor welcome building. The electricity can be used at Wimpole or it can be exported to the national grid for use elsewhere.

Facts and figures

Number of panels: 1,472
Tonnes of CO2 saved per year: 152
kWh of electricity generated per year: 350,000kWh (113 average UK homes or 50% of the Wimpole Estate's electricity use)
Electricity savings if all electricity used on site: £40,000