What is a carbon neutral building?

But Alter isn't convinced:

But if you are telling a green story, why put a three-storey building 42 feet up in the air so that everyone has to take an elevator to just get in? And what is the carbon footprint of making over half an acre of photovoltaics? After all, processing a tonne of silicon produces a tonne and a half of CO2, and a  square meter of solar cells appears to carry a debt of 75 kilograms of CO2, or 187 Tonnes...The engineer says that the photovoltaics will "avoid the pollution of 175 Tonnes of CO2 per year" so that carbon debt is paid off fast, but it still matters.

Alter also points out that there is little information available on what the building is constructed with. He then goes on to discuss the Centre for Interactive Research on Sustainability in Vancouver:

The Centre has all of the expected green gizmos, including enough photovoltaics to supply 30% of the building's requirements, a wind turbine, ground source heat pumps and "exterior and interior solar control strategies specific to each façade in order to minimize solar heat gain in interior spaces and to offset cooling loads. For south-facing facades use exterior louvered sunshades." It also has high performance glazing. But wait, there's more. Instead of throwing millions into photovoltaics to run the air conditioning, the centre is designed to run without them, thanks to operable windows, proper shading, effectively placed thermal mass, and natural ventilation...the Centre is designed to "ensure that the building works by itself and that it responds actively and autonomously to environmental stimulus." It collects its rainwater and uses it for irrigation and toilets. It has a green roof to reduce the rate and quantity of stormwater runoff from the roof.  Building materials are chosen for the lowest ecological footprint and greenhouse gas impact. A life cycle analysis is performed on all building materials to assess impact. All elements are demountable and bolted, designed for disassembly, yet with a 100 year projected lifespan. It is constructed from locally and sustainably harvested wood.

Alter concludes: "The CIRS building uses every trick in the book to go beyond carbon neutrality, and starts its useful life with half of the carbon debt of most buildings. The Satander building is draped in expensive and flashy green jewellery but borrowed deeply from the carbon bank; CIRS is frugal and prudent."