By Jan Dolezal
In many discussions and articles, “sustainable cities” and “vertical cities” are used almost as synonyms and many imply that floor-space-ratio correlates with sustainability. In this post I present arguments to challenge this popular belief.
Look at China for example. Shanghai Tower – the world’s second tallest building under construction boasts to be “sustainable best practice” and Broader Group’s Sky City which would become world’s tallest building is all intended as a role model of replicable sustainability.
Yes, there are clear energy efficiency advantages of going vertical. Less surface area per usable floor space results in less heat loss and less material required for enclosure. Large scale HVAC systems are more efficient. High density reduces the need for transportation.
But there are also numerous disadvantages to offset the gains. Bottom floors need to carry the full weight of all the upper floors, resulting in significantly more materials for primary structural systems. High buildings require extensive foundations to achieve stability in high winds and earthquakes, which drives material requirements further up. Less surface per floor space may result in less natural light. Smaller roof area versus equivalent horizontal buildings provides fewer opportunities for solar installations. Smaller parcel area does not provide opportunity for geothermal heating and cooling, which can sustainably reduce energy demands of a family house by 40-70% with ~10 year payback. Vertical transportation also requires additional materials to build and energy to operate. Given all these drawbacks the real resource efficiency advantage of vertical construction is at best questionable. Continue reading