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Natural Environment

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

Urbanisation increasingly requires us to build upwards. These vertical cities can be sustainable cities, but our skyscrapers must get smarter.

Hugo Cox
26 June 2020

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.

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.

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.

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.

For example, a business could need energy for air-conditioning on a hot summer day, and use power generated by solar panels on nearby houses, while residents are at work.

But local power generation is only one factor. To support a local network, you need a model for local consumption, which means building a marketplace where consumers and generators can trade.

Chain reaction

David Shipworth, Professor of Energy and the Built Environment at the Bartlett, believes that blockchain can play a crucial role in facilitating peer-to-peer energy trading, which could hold the key to the future of sustainable energy generation.

“Think of blockchain simply as a way of exchanging data that ensures an accurate record of that exchange between generators and consumers,” says Shipworth. Say, for example, that you buy a unit of energy that I have generated from solar panels on my roof, next door to you. My smart meter registers one more unit of energy exported to the grid; yours registers one more used.

High-rise buildings and high-density cities

High-rise buildings are commonly seen as providing the means of achieving sustainable density in high-population urban areas. Skyscrapers can accommodate large numbers of people within relatively small ground level footprints, enabling cities to leverage the benefits of proximity and avoid sprawl. Nonetheless, it is said that such “vertical villages” limit human interaction, inhibit creativity and innovation, and cast both a literal and figurative shadow over the urban realm. So, is building upwards really the best means of managing increasingly densely populated cities?

The blockchain register would work as an electronic ledger: a unit is added to my “produced” column and one is added to your “consumed” column. Everyone has a real-time copy of the ledger. So, you and I don’t even need to trust each other: transactions are recorded on everyone’s ledger, meaning that transactions are virtually impossible to forge. It is the perfect mechanism to support a market.

A local power network supported by blockchain could also support socially responsible investment. For example, a householder might support her daughter’s local primary school by buying energy produced by the school.

Shrinking the grid

The next obstacle is regulatory, says Shipworth. Currently, the tax and regulatory model for energy markets is partly a function of the huge costs of maintaining the grid. Today, the same amount is spent on keeping the UK’s National Grid running – strengthening wires, replacing transformers and pylons and so forth – as is spent on all renewable energy generation, says Shipworth. Reducing the size of wasteful national electricity grids would release money that could be used to fund sustainable power generation.

By then, perhaps the world’s skyscrapers will finally be paying their way in environmental economics.