Performance of an interseasonal heat transfer facility for collection, storage and re-use of solar heat from the road surface

The use of interseasonal heat transfer systems incorporating solar energy collectors in the road and shallow insulated heat stores in the ground is currently innovative and at the forefront of technology. A major instrumented trial of the technique was undertaken on an access road near Toddington which involved constructing two solar heat collectors (pipe arrays each 5m wide by 30m long installed at 120mm depth below the road surface) and two insulated heat stores of similar dimensions but at 875mm depth. One store was beneath the road and the other beneath the verge to simulate new construction and retrofit installations respectively. The solar heat recovered from the road surface was used to investigate the winter maintenance of the road surface and the heating of nearby buildings. The cooling of a building in the summer was also separately simulated. This report describes the design, construction, operation and performance of the instrumented test facility to recover heat from the road surface. The performance was monitored over a two year period which gave the opportunity for full seasonal assessments of the recovery of solar heat from the road surface, its re-use for ice-free winter maintenance of the road surface, and protocols simulating the winter heating and summer cooling of a nearby building. Numerical modelling and whole life costing of the recovery of heat for winter maintenance of a highway was included in the study.