The prevalence of green buildings is growing all around the world, encouraged and frequently even required by both client demand and government policies. The net-zero energy goal being widely adopted requires a significant reduction of building energy consumption as well as the integration of clean, renewable local generation
Although reducing energy use is important, the truly exciting prospects for managing building energy needs lie with incorporating renewable energy resources into the built environment. Several renewable technologies that are commercially available today can completely cover the consumption needs of buildings. Consisting primarily of photovoltaic (PV) and wind turbine systems, these renewable technologies are, however, variable, intermittent energy producers. To achieve the overall objective of mastering and optimizing energy use while also becoming more independent of the electrical grid, these energy resources can be coupled with storage or other more stable electricity generation technologies, such as combined heat and power generation (CHP). This post examines the various ways to achieve net-zero energy in buildings.
Solar/photovoltaic: a clean and cost-competitive energy source
Photovoltaic (PV) is the leading renewable energy technology for buildings. PV energy production has several benefits: solar energy is unlimited and available worldwide; it does not emit greenhouse gases (GHG) or other pollutants during operation; PV panels are silent; and PV systems require little maintenance. To make the technology even more attractive, the cost of PV systems has significantly decreased in recent years and the technologies also have become more efficient.
Photovoltaics are a good fit for buildings where they can occupy the unused rooftop area. Alternatively, they can use the car parking space, where in addition to producing energy, they provide protection to cars and individuals from sun and rain. Another option for new PV installations is to integrate them into the building architecture in what has become known as building integrated photovoltaics (BIPV
One common concern is whether the rooftop area is large enough to hold a PV system that will cover the energy needs of the building. Studies show that the majority of buildings have the technical potential to achieve the net-zero energy goals by covering 50% of their rooftop with photovoltaics – and many of them could produce even more electricity than they consume. Of course, this depends on several parameters such as the building’s location, how many floors it has, its principal use, and its plug and process loads. Some subsectors, such as warehouse, retail, and education, offer better opportunities to achieve the net-zero-energy building goal than other subsectors, such as hospitals, food services, or laboratories.
Combined heat and power (CHP): an efficiency boosting approach
Co-generation, or combined heat and power (CHP), is an energy production system generating both electricity and heat from a single primary source. This technology is a good fit for buildings or complexes of buildings (e.g., a campus) where it answers the demand for heat and in addition generates electricity. As a proven energy-efficient technology, CHP increases the primary energy utilization and reduces the greenhouse gas emissions.
Is cogeneration a renewable technology? Not really, but it is an effective approach to energy efficiency and CHP systems can use renewable technologies as a primary source. Possible fuels include biomass (biogas and biofuel) and geothermal for clean, low carbon footprint thermal and electrical energy production. In such a way, cogeneration can contribute to the integration of renewable energies in buildings.