Mr Marshall said: "There is a lot of enthusiasm at the moment for environmental certification for building, such as Passivhaus.
"But building schemes, although good business sense, are not legal requirements and in my opinion, are not tested enough and are too complex for everyone to understand.
"Part L of the building regulations for Scotland, England and Wales' technical standards means there is a lawful requirement to meet a certain level of energy efficiency in order to pass the regulations.
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"If the minimum level is met, it is classed as a nearly net zero building. As this is the legal requirement, it is therefore up to the client if they want to go beyond that to a zero-energy building.
"This can be done by meeting criteria two and three of the regulations which look at the fabric performance of a building and how much heat is lost through windows and floors and also overheating, and the reduced the needs of air-con or the capacity to have it.
"However, both of these criteria's are statutory guidelines, and so, are not lawful requirements. It is up to designers and builders to consider and deliver on these criteria's for a client in order to deliver net zero buildings without our own legal regulations in the UK.
"A lot of company's turn towards passive means to meet net zero but do not consider technology to mitigate overheating.
"This year, the lawful requirement will improve and ability to pass part L of the building regulations will get tougher, but there is still a lot to do for the policies to transition to have net zero buildings over the next 30 years.
"In the UK we take our innovative regulations for granted and don't use them enough to develop new guidelines.
"There is also a skill issue in the ability to build passively. Yes, there are training sessions on the approach to support net zero, but it is not enough to encourage businesses and company's to build these, instead they opt for the legal requirements which is the EU standard.
"The UK, in my opinion, is therefore not doing anything differently to Europe, yet we have the talent, the tools and the skills to go further than the EU and deliver net zero buildings.
"So it is important to ask ourselves the question: why are we relying on external standards when we do have the capacity to deliver net zero?"
