Energy performance modeling for buildings is a new field, but one that is getting a lot of interest under the impetus of government mandates and incentives. It's so new that there is no set of standard best practices. Energy modelers are having to make it up as they go. But this area is growing rapidly, and as government mandates for zero-energy buildings kick in, it is expected to grow exponentially. A Navigant Research study estimated that the energy efficient building market reached $307.3 billion in 2014 and that it will grow to $623.0 billion in 2023.
According to the 2014 scorecard released by the American Council for an Energy-Efficient Economy (ACEEE) Germany is #1 out of the 16 nations studied in the World for energy efficiency. In Germany buildings currently account for 40 percent of power consumption and a third of CO2 emissions.
In September 2010 the German Government released a 40 year masterplan for revolutionizing the German energy supply that includes an aggressive plan for energy conservation focusing on reducing the energy demand from buildings. According to the plan new insulation standards are to be introduced the government wants all buildings in Germany to be refurbished in line with new standards by 2050. It also wants to cut the national heating requirement by 20 percent by 2020 and by 80 percent by 2050. Germany is part of the EU which is very aggressive in improving the energy efficiency of buildings.
The EU Energy Saving Ordinance mandates a 25 percent reduction in energy use for all new residential and non-residential buildings built from January 1, 2016. And as of 2021, the EU’s nearly zero energy standard will apply to all new buildings.
The EIA has just released information on building energy efficiency programs in China. Unlike many other countries, the Chinese government has focused a lot of regulatory attention on existing buildings. The overall objective of the Chinese government is to raise the level of existing buildings to satisfy regulations governing new construction. In 2011, the government implemented regulations that mandated a 10% reduction in energy consumption per square meter for commercial buildings by the end of 2015. It also mandated a 15% reduction for commercial buildings with more than 20,000 square meters of floor area.
Energy certification of buildings is a key policy instrument for reducing the energy consumption and improving the energy performance of new and existing buildings. In the U.K. since 2008 public buildings over 1,000 m2 must display a Display Energy Certificate (DEC). DECs document the actual energy usage of a building and look similar to the energy labels provided on new cars and electrical appliances. In the U.S. six cities and two states have passed laws requiring energy benchmarking of existing buildings. It is estimated that these laws will affect 4 billion ft2 of floor space in major real estate markets. In Australia commercial buildings 2000 m2 and over are required by the Building Energy Efficiency Disclosure Act 2010 to have a Building Energy Efficiency Certificate (BEEC). In Jakarta a new green building code became mandatory for existing and new buildings in early 2013. The code covers all large buildings in Jakarta including office buildings, shopping malls and apartment buildings larger than 50,000 square meters; hotels and healthcare facilities larger than 20,000 square meters; and educational facilities larger than 10,000 square meters.
The European Union's SUNSHINE program is intended as a step towards toward standards for measuring the energy performance of buildings and a way to contribute to improving the energy efficiency of buildings. SUNSHINE is based on open standards such as CityGML from the OGC.
In the United States according to the Environmental Protection Agency (EPA), buildings are responsible for 65 % of electricity consumption. An important motivation for energy efficient buildings in many jurisdictions are aggressive building codes that push energy efficiency. For example, the 2013 California Green Building Standards Code (Title 24) is one of the first “green” building codes. Other motivations are customer driven certification such as LEED and other "green" certification - LEED v4 incorporates up to 18 credits for demand response - and financial incentives from local governments and power utilities to reduce energy consumption, peak load or both.
Government mandates for zero energy buildings (ZEB) have been introduced in E.U., the U.S. and Japan. According to Navigant Research, global ZEB revenue is expected to grow from $629.3 million in 2014 to $1.4 trillion by 2035.
Energy performance modeling is an essential tool for estimating the energy requirements of a new or existing building. An energy performance analysis can determine how much energy a building will consume in a year, assess the most cost effective insulation and glazing, and assess other things that can be done as part of the building design to optimize energy usage. An energy analysis requires data - geometry of the building, performance characteristics of materials, geolocation and orientation of the building, and so on. Simulation applications include local environmental conditions and involve thermal modeling, daylight and airflow simulations. Thermal modeling includes energy consumption, thermal comfort, CO2 emissions, renewable energy integration, and electric power load. Natural lighting includes visual comfort (glare) and the reduction of energy use through natural lighting. Airflow simulation includes external wind simulation, internal airflow simulation, clean room ventilation, and reduction in electrical load as a result of using natural ventilation.
There are many energy analysis tools available (lighting, thermal, emissions, water usage, etc) , many are very complex, and the volume of data that is required is increasing exponentially. Many energy modelers follow a best-of-breed approach so interoperablity is a major challenge in improving productivity in energy performance analysis.
Increasingly for energy modelers the natural place to start is with a Building Information Model (BIM). There are several reasons for this. First of all it is what many of the energy performance analysis packages expect and it is supported by the gbXML standard. Secondly it allows all the information required by the architect, engineers and construction contractors to be accessed in one place. And thirdly it helps in communicating the results of the energy performance analysis to the people who need it including heating and cooling, lighting and other types of engineers, all of whom may require the same information but communicated in different ways.