(The guidance on energy performances is indicative only of the house designs illustrated. The DER ratings quoted should not be assumed for any house type as variation of specifications as well as size and shape of the building will effect the energy performance. Xtratherm can advise on calculation and give guidance on indicative ratings, but it is advised to contact a CSH Consultant at an early stage in the design process. Xtratherm accepts no liability for errors, omissions or claims arising from the use of this information.)