Original data available from: UK DATA ARCHIVE: Study Number 7518 - National Energy Efficiency Data-Framework, 2014
* Notes:
* This dataset is a sample of just over 4 million households which have had an Energy Performance Certificate from the full NEED 'all dwellings' dataset
* Is this all those who have had an EPC or a random sample of all those who've had an EPC?
* Sample bias is unkown - which kinds of dwellings have an EPC?
* Gcons<year>valid variable has undefined labels: G, L, M = ? Presumably 0 = off gas & V = valid?
* ideally DECC should set missing to -99 to aid re-coding and avoid unpleasant surprises in naive analysis!