This Cost Guide focuses on typical retrofit interventions related to operational carbon emissions. Any buildings with non-standard features or unusual specifications may fall outside of the ranges given. Other aspects such as whole life carbon, overheating, air-quality, wellbeing and the inter-dependencies between these interventions are important and must be taken into consideration when designing a retrofit. This is a rapidly evolving field and the latest guidance including (but not limited to) RICS, UKGBC, LETI, CIBSE and RIBA should be followed.