Reusing existing buildings is set to be the next big thing because it is greener and cheaper than new build. Hampshire council's refurbished headquarters has kicked off this trend; a gas guzzling sixties eyesore has been transformed into one of the UK’s most energy efficient offices. It pioneers a way round the problem of naturally ventilating buildings next to noisy, polluted roads and is a model for a new generation of green office buildings that reuse existing structures.

In other news, the Part L consultation closed this week and already glitches are being discovered in the software used to calculate compliance. Modelling by engineer Hoare Lea showed the software heavily penalises biomass boilers, ventilation system that recover heat energy from expelled air and efficient displacement ventilation systems.

While we are on the subject of cock-ups the new water regs have been delayed for six months because of a row over wording with Europe. Finally we have the latest installment of the Passivhaus diaries and a feature that takes an overview of the whole project.

Also, to mark World Green Building Day on Wednesday we will be featuring a video interview with housing minister John Healey. Look out for that and see how Britain's green building policies compare to other industrial nations in our global guide.