The cost of high living – Part 2: Power to the tower

When it comes to how to build at scale more sustainably, the principles of Passive House could prove to be a valuable resource. The stringent design standard was developed to reduce the energy required to heat or cool a building by harnessing the power of the sun and internal energy sources, while conserving heat with airtight construction methods.

In the fast-expanding city of Gaobeidian, in China’s central Hebei province, 1.2 million square metres of living space has just been Passive House-certified. But the application of these standards to commercial buildings can provide particularly big dividends.

In 2015, a full Passive House retrofit of a university building in Innsbruck, Austria, reduced heating demand from 180 kWh/m² a year to just 21 kWh/m² a year, reports the Passive House Institute. In 2018, Klinikum Frankfurt Hoechst, the world’s first certified Passive House hospital opened.

Typically, electricity consumption in a hospital is between three and four times higher per m2 than that of an equivalent-sized residential building, the institute estimates. According to its figures, 40-60% of a hospital’s energy use can be saved using a Passive House construction.

Dr Wolfgang Feist, director of the Passive House Institute, says that sourcing power entirely from locally generated renewables is a far more useful measure of a self-sustaining building than the popular “annual net zero” balance where electricity fed into the grid is offset against energy consumed. One reason is that large-scale electricity grids waste a proportion of the power that runs through them, and this is not taken into account in calculations. In 2014, 8.3% of all electricity generated across the world was lost in transmission, according to the World Bank.

The Innsbruck building combines renewable generation, including a groundwater heat pump, a solar thermal system and solar panels, with traditional Passive House building methods to reduce heat loss. “The combination of energy efficiency and renewables is the futureproof solution for all buildings, including multi-storey projects… [In the Innsbruck building] the actual amount of regionally and seasonally available renewable energy is taken into account so that a completely sustainable supply system becomes possible,” says Feist.

The Innsbruck building combines renewable generation, including a groundwater heat pump, a solar thermal system and solar panels, with traditional Passive House building methods to reduce heat loss. “The combination of energy efficiency and renewables is the futureproof solution for all buildings, including multi-storey projects… [In the Innsbruck building] the actual amount of regionally and seasonally available renewable energy is taken into account so that a completely sustainable supply system becomes possible,” says Feist.

Since battery technology doesn’t yet allow a building’s self-generated power to be stored onsite – which, if it were possible, would allow heat or power generated in the summer to be kept for use during the winter – the best solution is creating buildings that need less energy in the first place, and can generate all they need.

Until buildings generate their own energy, smart technology may localise electricity grids, reducing transmission waste. Shrinking the grid to a very local level is almost as effective as removing it altogether, since the further electricity must travel, the greater the waste. (Ironically, the growth of renewables has, in some cases, increased the distances across which electricity must be transmitted.)

Wide-scale adoption of solar panels and the growing number of local wind farms raises the prospect of a future where local energy demands are met by locally generated electricity, which would vastly reduce waste from transmission.