Feasibility of achieving net-zero energy performance in high-rise buildings using solar energy

As part of a broad strategy to reach net-zero greenhouse gas emissions and limit global warming, many countries are requiring all new buildings to have net-zero energy use. This requires that on-site energy use not exceed on-site generation of renewable energy (taken here to be solar energy), or equivalently, that the building Energy Use Intensity (EUI, kWh/m²a) not exceed the supply of on-site solar energy (electricity and heat) per m² of floor area per year. On this basis, we find that achieving net-zero energy performance in an archetype 40-story square building in 16 different cities of North America requires EUI of 17–24 kWh/m²a using PV panels, and 19–28 kWh/m²a using PVT collectors. Changing building orientation to a non-square floor shape can improve maximum permitted EUI by up to 50% in PV and 60% in PVT case. Conversely, the best-performing residential and commercial buildings have EUIs of 50–75 kWh/m²a. Only if building heights are limited to 5–10 floors does the available solar energy, and thus the permitted EUI, reach 50–75 kWh/m²a. Therefore, we recommend that policymakers not require high-rise buildings to be net-zero energy, unless they are prepared to limit building heights to 5–10 floors.