You might have heard wild-eyed sounding rumors in the past about the European Union legislating net zero buildings. Those weren’t rumors.
A few years ago, the EU parliament required all new buildings to be “nearly net zero” (being defined by each state) starting in 2019. Existing ones that undergo major renovations will have to hit energy performance targets set by the member states. In the UK, new homes need to hit that target even sooner – they need to be carbon neutral by 2016.
Now California (any surprise?) has established a net zero beachhead in North America. Under an executive order issued by Governor Brown on April 25th, by 2020 half of new State buildings and major renovations will be net zero and all by 2025.
If you’re wondering how they are going to design these buildings, one could look to the net zero projects on the drawing boards in New York City: P.S. 62 on Staten Island (starting this year), Solar 2, and Cornell’s Roosevelt Island campus. And if they can do it, perhaps it’s time that we follow California and the EU’s lead?
That would be a bad idea. The first part of net zero – extraordinary load reduction – is something that all new buildings could and should achieve. We’re seeing it with these projects and we’re seeing it with Passive House. But the second part – generating solar electricity onsite – just isn’t possible for many buildings in New York. It’s no coincidence that all three New York net zero projects have large roof to square footage ratios, and are also in open areas of the city without neighboring buildings to shade their roofs. A high-rise just doesn’t have enough roof area for PVs to generate its own energy and the only way they could meet a net zero mandate would be to purchase expensive renewable energy credits. According to our research director, Richard Leigh, “for almost any commercial or residential use, even with efficient lighting and appliances, the solar resource to get above three stories and meet net loads with on-site collectors just isn’t there, even out in the open countryside.”
So let’s build super energy-efficient buildings and install whatever onsite renewables we can. But as we look towards the next generation of green buildings, let’s remember that while net zero can be done for low-rises it doesn’t work for high-rises.