Since October 2008 if you make your property available for rent you should have an Energy Performance Certificate (EPC) for it. This certificate has to be made available to any prospective new tenant when they view the property and when you let the property the new tenant should be provided with a copy of the EPC together with the rental contract. If you have bought the property since 2008 then it should have an EPC and you can use this certificate. To check if your property has an EPC go to www.epcregister.com
The EPC contains recommendations on how to make your property more energy-efficient, at present there is no requirement for you to improve the property. However from 2016 if your tenant asks to improve the energy efficiency of the property you will not be allowed to unreasonably refuse and after 2018 you will not be allowed to let your property if the Energy rating is below E. It therefore makes sense to build energy efficiency improvements into your building maintenance programme from now on.
If you do not have an EPC, I can provide this for you. For more information about the assessment process download Landlord & Tenant Leaflet. To enable me to make an accurate assessment of your property I need as much information as possible about the age, construction, heating, hot water and lighting systems, so it is helpful if you assemble this information ready for my visit. You can download a check-list here Owner Questionnaire-Checklist of the type of information I shall need.