When Carbon Neutral Buildings Don't Add Up

satander cucinella exterior image

via Mario Cucinella
Mario Cucinella is one of the greener architects in Italy; I loved his Casa 100K euro that we featured earlier. His Satander building is interesting too, billed as the first "Zero CO2 office building in Milan." But the three storey building sits on stilts, so everyone will probably take the elevator, which they might not have done if it sat on the ground like a conventional building. The Centre for Interactive Research on Sustainability in Vancouver, on the other hand, takes carbon neutral to another level.
satander cucinella roof image

via Mario Cucinella

The Satander Building in Milan, by Mario Cucinella

The Satander building, Cucinella tells us, is raised 13 metres above ground level with piazzas, pathways and green areas below." And, "The facades are glazed with high technology selective glass and the treatment of the glass varies depending on the orientation of the façade."

But wait till you get to the roof: It's covered with 2,500 square meters (26,909 square feet) of photovoltaic panels that "produce enough renewable energy to completely satisfy the building's cooling needs" of 304,000 kWh/year. The engineer for the project notes that these cost € 1.800.000 (US$ 2.5 million), well over a quarter of the budget and twenty bucks a foot on the building's hard costs. There are other green features as well, such as pre-cooling the air with ground water, heat pumps instead of boilers, and carefully engineered sun shades on the south-west facade to "maximize the solar radiation for free heating in winter, and to minimize it in the summer to avoid heating."

satander cucinella under image

via Mario Cucinella

Indeed, there is a lot going on here. 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. Production of semiconductors like solar cells also uses a lot of chemicals like sulfur hexaflouride or nitrogen trifluoride, both notorious greenhouse gases. 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.

There is little information available about what the building is made of, and no accounting of the carbon footprint of its materials and construction, so it is hard to really determine at what point this "zero carbon" building overcomes the carbon debt of its construction, but I suspect it will be a while. And isn't it something that should be considered?

cirs busby perspective image

via Busby Perkins + Will
The Centre for Interactive Research on Sustainability in Vancouver by Busby Perkins + Will
Peter Busby of Busby Perkins + Will thinks so. He is designing the Centre for Interactive Research on Sustainability in Vancouver to look at the full range of issues that make a building "sustainable" or "zero carbon." The facility is designed to be a "test-bed and research laboratory for the most advanced building sustainability technologies in North America."

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.

cirs busby aerial perspective image

via Busby Perkins + Will

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. Says Busby Perkins + Will, 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.

cirs busby interior perspective image

via Busby Perkins + Will

I could go on, but the main point is simple: 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; CIRC is frugal and prudent. In these times, that is a virtue.

This article was adapted and expanded from an article I wrote for Azure Magazine.

More on Peter Busby:

Collin's original post on Cirs: Accelerating Sustainability: New Super-Green Research Lab
Smart Condo by Peter Busby

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