The EU executive is under pressure to ratchet up green energy standards for buildings, as it prepares a further batch of legislation to tackle the climate emergency. The European Commission is expected to propose mandatory energy efficiency upgrades for buildings in the EU in legislative proposals published on Wednesday, but MEPs and Green NGOs fear they will not be strict enough. The Guardian understands that the worst-performing houses and flats will be required to be renovated to energy-efficiency standard F by 2030, then to E by 2033. The most energy-wasteful public and non-residential buildings will have to hit the F grade by 2027 and E by 2030. EU energy efficiency classification runs from A to G, with G being the worst in class. Buildings account for 36% of the EU’s greenhouse gas emissions, meaning millions of homes, offices, shops, schools and hospitals will have to be renovated, if the bloc is to meet a pledge of net zero emissions by 2050. The draft law on buildings, accompanied by plans for greener transport, cutting methane and revising EU energy rules, form part of the EU’s green deal to transform its economy in less than three decades. Another tranche of proposals, including on renewable energy and industrial pollution, were released in July and are going through the EU legislative process. Under the buildings plan, all new constructions would have to be net zero-emissions by 2030. EU member states would face a legal obligation to draw up a timeline to ensure their buildings were net zero emissions by 2050. The biggest controversy has centred on energy efficiency targets for existing buildings, triggering frantic last-minute rewrites. More than 85% of EU buildings were constructed before 2001 and the vast majority are expected to be still standing in 2050. Frans Timmermans, the commission vice-president in charge of the EU green deal, has called for a “renovation wave” based on stronger regulations on the energy performance of buildings. But an ambitious early draft of the EU’s updated energy performance in buildings directive by his team ran into opposition from a Brussels watchdog. Timmermans’ officials had proposed that all residential buildings sold or rented after 2027 should achieve energy class E. But the Regulatory Scrutiny Group, a body of officials and experts, overruled the idea, saying the commission risked stepping on powers that belonged to national governments. Since then a cross-party group of MEPs has urged the commission not to blunt its ambition. Mandatory targets are key to bring buildings in line with the EU’s 2030 and 2050 climate targets, wrote MEPs from the Greens, centre-right European People’s party and centrist Renew groups in a letter to Timmermans and other commission officials. “[The] ‘worst performing buildings’ are often inhabited by the energy poor and the renovation of those buildings clearly pays off in terms of costs, energy consumption, and health. Delaying action to 2030, and only covering part of our homes or limiting to the F and G classes is just not enough.” The buildings plan has to be approved by EU ministers and the European parliament. Adeline Rochet, a senior policy adviser at the E3G thinktank in Brussels, said minimum energy performance standards were a cornerstone of the commission’s strategy. “A good energy performance certificate regime is necessary but it won’t be sufficient. If it’s not backed by mandatory energy standards it won’t be enough.” One European parliament source said there was not enough detail in the latest plans about how millions of buildings were going to hit the best energy efficiency standards in less than three decades. “We only know that magically in 2050 all of them should be in energy class ‘A’, but the timeline for this is not spelt out and that is the big problem.” The source added that there were too many exemptions for historic buildings. “The exemptions are formulated in such a broad way that maybe all the buildings in Italy will be exempt.” Ciarán Cuffe, an Irish Green MEP, said it was essential that minimum energy performance standards (Meps) were included in the revision of the energy performance in buildings directive. “ have the potential to improve our worst-performing homes, to alleviate energy poverty, and significantly reduce the emissions from the EU’s building stock.” “Meps will help to increase the energy efficiency of buildings and therefore they reduce energy bills for citizens, which especially benefits those at risk of energy poverty. In order to make sure that vulnerable households are protected, we should have targeted funds that would act as adequate social safeguards to help ensure the affordability of housing at a national and local level.”