Technical Booklet F1 Conservation of Fuel and Power in Dwellings·Page 51·3.60
Upgrading to best practicable standard when 15-year payback not achievable
Where upgrading to specified standards is not technically or functionally feasible or cannot achieve a simple payback of 15 years or less, elements should be upgraded to the best practicable standard that is technically and functionally feasible within a 15-year payback period.
Where upgrading to the above standards is not technically or functionally feasible or would not achieve a simple payback of 15 years or less, the element should be upgraded to the best practicable standard that is technically and functionally feasible which can be achieved within a simple payback period of 15 years. Guidance on this approach is given in Appendix B.
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