Energy Efficient Cities: A Quick Introduction to Passive and Active Design

There are two distinct approaches that will work in unison to meet the growing energy demands of our urban future: passive design and active design. Active approaches depend on the development of new technologies and passive solutions integrate into current urban flows.

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Illustration: © IoT For All

There are two distinct approaches that will work in unison to meet the growing energy demands of our urban future: passive design and active design. Active approaches depend on the development of new technologies such as communication systems, power storage and sensors to introduce energy efficient processes into the dynamic flows that constitute our urban economies. The ability to build these systems depends on both public- and private sector financing of research and development. Passive solutions, such as natural ventilation, smart materials and intelligent transit planning, rely more heavily on design research and process planning processes and operate within the static subsystems within urban flows.

Active Design: Infrastructure Investments for Energy Efficiency

Intelligent microgrids are one of the more important active infrastructural investments for energy efficiency. By leveraging distributed generation, electricity storage and responsive, automated scaling of electricity supply to meet live demand loads, these systems make urban electricity transmission more reliable and efficient. Distributed generation also allows for easier integration with renewable energy sources such as small wind or photovoltaic arrays, which on their own may not be large enough to merit standalone integration into current electric utilities.

Traffic and transit infrastructure is another field which requires active design such as the invention of new, efficient modes of private transit, the electrification of public transit systems and smart traffic management that leverages a distributed system of roadside sensors to decrease travel time, energy expenditure and therefore also emissions. Additionally, new approaches with high research and development (R&D) requirements, such as shared autonomous vehicles, may minimize the amount of automobiles on the road and maximize the energy efficiency per mile traveled, even more so if electrified.

Passive Design Solutions

Passive solutions at a building scale are also important to consider as they allow for direct capital investment while minimizing recurring operational costs. These approaches rely on leveraging natural phenomena and the smart use of materials to adjust heat absorption and emission without added energy inputs. In housing, some standards such as the Passivhaus standard, which focuses on natural ventilation and super-insulation are already prominent in Germany and beginning to gain traction in parts of New York. Other technologies include solar heat collectors, which absorb daytime heat in the liquid medium, underground ventilation, which routes air through subterranean tubes to naturally cool or heat it to a baseline temperature and seasonal heat storage.

Larger scale solutions such as the intelligent layout of building groups for maximum heating and ventilation, street set-back laws and considerations for the urban canyon effect (which raises the temperature and increases wind velocity) can also be implemented by governmental players to maximize the passive potential of both privately and publicly owned urban structures. Over the next three articles, you will learn about how passive and active design methodologies are used in building-level solutions, large scale urban infrastructure and urban transportation.