It’s been seven months to the day from the “switch on” of the 300kw marine source heat pump system at Plas Newydd on Anglesey. We are now into full heating season operation, and have completed a fantastically busy summer at the property. So thought I would stop by and assess how well the system is doing before I go into mince pie overload.

Firstly, I took a walk down to the foreshore and was pleased that despite the disruption caused by the construction of a crane lifting platform earlier in the year; the grounds have recovered nicely and thanks to the efforts of the property gardens team have softened around the edges to ensure that as we proceed into the new year our visitors will be able to fully enjoy the historic viewpoint across the Menai Strait opened up once more in order to place the pump-house on the foreshore.

The project has had a huge amount of interest and Keith and I spent the summer showing people the technology as well as the National Trust approach to the integration of appropriate sustainable solutions which is the basis of our REI programme across the organisation.

As with every new system, we were required to “fettle” in order to make it as efficient as possible in operation, but thanks to my trusty assistant, we have settled into full operation nicely and our understanding of the conservation heating needs of the mansion is paying dividend as the previously “cooked mansion” is now taking full advantage of the consistent lower flow temperatures of the heat pumps and thermal mass of the building to ensure we maintain our sensitive building and its contents in-line with our accredited museum requirements.

The national Trust utilises heat to manage relative humidity within our buildings working within a range of 40% to 65% RH. You can see from the screen capture that only the medieval cellar areas have dipped below the 40% line. This was always going to be the challenging area as the cellars are extensive and by their very nature difficult to manage and control. Our preventative conservation specialist visited last Thursday and was extremely pleased with the monitoring being much improved on previous results, and consistent across the property (the wiggly lines follow the same pattern – see I am technical).

Finally, how are we doing performance wise?

As you can see the system is performing better than calculated. To date we have a cumulative CoP of over 4 (the system was designed to achieve 3.4). When you take into account seasonal variations and factors such as circulation pumps operating even during the summer, as we heat our mansions during the summer as well in order to control relative humidity, we continue to perform above calculated with an SPF of 2.8.

What does this mean for the property itself – A sustainable conservation heating system which allows greater control and protection of our buildings and contents; A new chapter in the story of this special property and its maritime history; and for those of you who cut to the chase – an operational saving of £18,000 compared to the previous oil fired heating system. This is money that is now being allocated directly to conservation instead of simply paying the heating bill.

I think a celebratory mince pie is in order.