Caryn Hibbert

Green Technologies at Thyme

by Caryn Hibbert At Thyme 1 Jan 16

Thoughtful technologies ensuring we operate in a mindful way

One of our most magnificent spaces is our Grade 2 listed Tithe Barn. Dating back to the early 17th century, its purpose was to serve the farm, for flail threshing and the storing of grain or pulse crops and would have been filled right up to the eaves, or even higher. The small square ventilation holes in the rubble stone walls were to circulate the air and help dry and cool the grain.

It was important in the restoration to conserve this huge simple space, to find a purpose for it that was sustainable, but respected its architecture, farming heritage and its environment. Adjoining the Cookery School, it now provides a majestically simple and beautiful dining area, both humble and impressive it continues to work with the land, the farm and the vegetable gardens. The original ventilation holes now form little windows, which, when lit with small candles, create a very special, almost ecclesiastical, feel.

Its restoration presented some challenges; not least to create a warm space that was well ventilated: ‘freezing like a barn’, it could not be. The system needed to be invisible, ecologically sound and comply with ventilation and insulation regulations, whilst respecting its Grade 2 listing.

The first step was to insulate the building as well as possible. This was limited to the roof, as the walls are solid stone rubble, but with careful design this allowed the rustic beams to remain visible and a main feature of the interior.

The provision of heat is from a closed loop heat pump system, which takes water from an aquifer 5.2 meters below the ground at a constant 12°C. This water is cooled to 5°C, transferring the heat to a buffer tank at 35°C. This hot water is pumped around the under floor heating system, the efficiency is such that the heat energy output is 4 times the electric energy input, making this a very carbon efficient and economical system. The extra water stored in the buffer tank means the system is very responsive to changes in the heating requirements. An additional and significant contribution to the efficiency of the system is the thermal conductivity of the floor finish, where flow-tech concrete has double the conductivity of conventional concrete.

The system needs to minimise heat loss, so the ventilation requirement to replace all the air in the barn 3 times every hour presents a significant problem. The solution was to install a heat exchange system which removes 80% of the heat from the air extracted and transfer it to the incoming fresh air. The ventilation ducts are concealed under the floor behind discreet grills.

The result is a very special space: the warm stone floors give it a real heart and make it an intimate, yet impressive, stage for all sorts of special occasions.