may also be referred to as sustainable design. Apart from the design field, around 40% of energy consumption and 13% carbon emissions are related to building HVAC systems operation. In order to mitigate rapid climate change, renewable energy sources, such as solar and wind energy are adopted by the building industry to support electricity generation. However, the electricity demand profile shows imbalance between supply and demand, which is known as the ‘duck curve’. This could impact on maintaining grid system stability. Therefore, other strategies such as thermal energy storage systems are developed to achieve higher levels of sustainability by reducing grid peak power. A push towards zero-energy building also known as Net-Zero Energy Building has been present in the Building Science field. The qualifications for Net Zero Energy Building Certification can be found on the Living Building Challenge website. Post-Occupancy Evaluation (POE) POE is a survey-based method to measure the building performance after the built environment was occupied. The occupant responses were collected through structured or open inquiries. Statistical methods and data visualization were often used to suggest which aspects(features) of the building were supportive or problematic to the occupants. The results may become design knowledge for architects to design new buildings or provide a data-basis to improve the current environment. Certification Although there are no direct or integrated professional architecture or engineering certifications for building science, there are independent professional credentials associated with the disciplines. Building science is typically a specialization within the broad areas of architecture or engineering practice. However, there are professional organizations offering individual professional credentials in specialized areas. Some of the most prominent green building rating systems are: BREEAM (Building Research Establishment Environmental Assessment Method), which is the world's longest established sustainable building assessment system, developed by the Building Research Establishment; LEED (Leadership in Energy and Environmental Design), developed by the U.S. Green Building Council; Green Star (Australia), which is the main green building rating system in Australia, developed by the Green Building Council of Australia; WELL which is delivered by the International WELL Building Institute and administered by the Green Business Certification Inc.; CASBEE (Comprehensive Assessment System for Built Environment Efficiency), which is the main green building rating system in Japan. There are other building sustainability accreditation and certification institutions as well. Also in the US, contractors certified by the Building Performance Institute, an independent organization, advertise that they operate businesses as Building Scientists.