3D building models: An ‘alternative’ route with energy efficiency

3D building models: An ‘alternative’ route with energy efficiency

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With buildings consuming one third of the world”s total energy, improving energy efficiency of buildings, both new and existing, has become a global priority today. Explore how the convergence of 3D BIM, geospatial and energy modeling is enabling designers to reduce the energy footprint of existing structures and design new, highly energy-efficient structures.

 

In the world”s warming climate, the increasing demand for electric power is being increasingly met by alternative fuels, nuclear power, natural gas, renewables such as solar and wind and through energy efficiency. In many jurisdictions, energy efficiency provides the least expensive alternative fuel.

The International Energy Agency (IEA) estimates that residential, commercial and public buildings account for one-third of the globe”s total energy consumption. In 2008, buildings accounted for 72 percent of electricity use in the US. The proportion of energy consumed by buildings is expected to increase in the future owing to the emerging economies. This has made improving the energy efficiency of buildings, both existing and new, a global priority.

The European Union (EU) has taken the lead in improving the energy efficiency of buildings. The EU has mandatory carbon emission reduction standards, referred to as the 20-20-20 standard, which, among other things, requires the EU to improve energy efficiency by 20% by 2020. In 2002, the European Commission promulgated the Energy Performance of Buildings Directive (EPBD) which requires all EU member states to upgrade their building regulations and to introduce energy certification schemes for buildings.

In Germany, buildings currently account for 40 percent of power consumption and a third of CO2 emissions. The German 40-year master plan calls for aggressive energy efficiency policies including new insulation standards and for all buildings in Germany to be refurbished in line with the new insulation standards by 2050, reducing energy requirements for heating by 20 percent by 2020 and by 80 percent by 2050, and providing tax relief on energy taxes to companies contributing to energy savings.

In the US, Executive Order 13423 is a national initiative to reduce the average annual energy consumption of Federal buildings by 30 percent by 2015. The Energy Policy Act of 2005 is another directive that requires that Federal buildings be designed to use 30% less energy than the industry standard ASHRAE Standard 90.1. In its current budget, the US Department of Energy has allocated USD 310 million to promote energy conservation, specifically improving the energy efficiency of commercial and residential buildings.

Nearly zero energy buildings: A major area of focus in the EU is nearly zero energy buildings. A nearly zero energy building on an average generates as much energy from renewable energy sources as it consumes. For new buildings, the EPBD recast has fixed 2020 as the deadline for all new buildings to be nearly zero energy. For public buildings the deadline is even sooner, by the end of 2018. For existing buildings, EU member states are required to draw up national plans to increase the number of nearly zero energy buildings.

In the US, the Energy Independence and Security Act of 2007 (EISA 2007) requires that by 2030, all new Federal facilities must be net zero energy buildings. The US Department of Energy is funding research into net zero energy buildings. Pike Research has projected that as a result of the recast EU EPBD Directive and similar legislations in other parts of the world, such as Japan, worldwide revenue from net zero energy building construction will grow at an annual rate of 43% over the next two decades, reaching USD 690 billion by 2020 and USD 1.3 trillion by 2035, with much of the growth occurring in the EU.

The International Energy Agency (IEA) has announced the Building Energy Efficiency Policies (BEEP) database. The BEEP database collects information on buildings energy codes including minimum energy performance requirements that focus on achieving zero energy buildings, buildings energy labels which increase awareness about energy consumption of buildings, and incentives schemes for capacity building, technical assistance and raising awareness. The database includes information from all IEA member countries as well as China, India, Tunisia, South Africa and Russia. The IEA secretariat encourages all countries to submit information on their buildings energy efficiency policies to be included in the database.

Municipalities, electric utilities and energy-efficient buildings: IDC Energy Insights” top 10 predictions for the North American energy and utility sector identified smart buildings as a top priority for electric power utilities in 2012. One of the ways that power companies in the US are increasingly turning to is demand response (DR). DR is an agreement between the power utility and a customer, such as a residential, industrial, or commercial site, which allows the utility to reduce the power demand from some of the facilities or equipment at the customer”s site. Recently, the federal regulator (FERC) has mandated that a negawatt should be compensated at the same rate as a megawatt. In other words, customers should be paid the same for reducing the load by a megawatt as a generator is paid for generating a megawatt. The US Green Building Council (USGBC), Lawrence Berkeley National Labs and the Environment Defence Fund, supported by Southern California Edison, have started the Demand Response Partnership Program (DRRP) to encourage greater adoption of DR by the commercial building sector.

The Ontario Energy Board (OEB) has set an aggregate target of 1,330 MW of provincial peak demand reduction by the end of the four-year period and 6,000 GWh of reduced electricity consumption accumulated over the four-year period. In Ontario, new buildings must comply with the Ontario Building Code, basically ASHRAE 90.1. In addition, new buildings with 40% or more external glazing are required to conduct an energy assessment. After January 1, 2013 all new buildings will have to exceed ASHRAE 90.1-2010 by 5%.

Building information modeling (BIM)
BIM is an intelligent model-based process that helps owners and service providers achieve better business results by enabling more accurate, accessible and actionable insight throughout project execution and lifecycle. Architects, engineers and construction companies are increasingly adopting BIM because through enabling collaboration and automating activities such as clash detection and bill of materials generation, it enables them to reduce the risk of budget schedule overruns. But BIM also helps enable activities that reduce the energy footprint of buildings.

According to a recent study by Global Insight, only 6% of worldwide construction activity incorporates green technology at present. Driven by regulation, owner and investor demands, resource cost, security concerns and third party standards, it is projected that this will increase to 75% by 2020. The McGraw-Hill Construction report Green BIM: How Building Information Modeling is Contributing to Green Design and Construction forecasts that the growth of the green building market will accelerate adoption of BIM. The convergence of BIM and sustainable design, which McGraw-Hill refers to as Green BIM”, is just getting started, but a sharp increase in Green BIM is expected in the near future.

Environmental analysis and certification programmes like BREEAM, LEED require natural lighting, solar radiation, wind, renewable energy and noise analyses all of which require integration of geospatial information and local climactic conditions with the building design information which is gathered, stored and used in BIM. A BIMbased approach to energy modeling is applicable to new or existing buildings.

Improving energy efficiency of existing buildings
For an existing structure, it is necessary to measure the building”s current performance. This typically involves compiling information from historical photographs, construction drawings and field observation. High definition laser scanning is frequently used to collect accurate three-dimensional physical and spatial information. Laser scanning process creates a three dimensional point cloud of the surface it scans. With this approach an accurate building model can be created in a fraction of the time that it would take to perform field measurements or interpret the design from existing construction drawings. From the 3D point cloud, a dimensionally accurate BIM is created, which acts as a coordinated repository of what is known about the building. This includes information which would impact the performance of the building such as glazing types, material thermal properties, HVAC zones and occupancy patterns.

With the geometry and other necessary information collected in the BIM model, together with the geographic location and orientation of the building, energy analysis can be performed that incorporates local historical insolation and weather information including temperature, moisture, wind and psychrometric data. The analysis generates a big picture assessment of how the building is performing at its location and in its expected climate. This helps create a working hypothesis about the building”s energy behaviour and to identify areas where there may be opportunities for energy savings including water infrastructure, daylighting and lighting efficiency, renewable energy generation (solar PV), mechanical (heating and cooling) waste and efficiency.

Improving energy efficiency of new buildings
Jean Carriere of 3DEnergy is a building energy usage analyst who works with architects and engineers to optimise energy usage for new buildings. He typically starts with a BIM model of the building provided by the architect. From the architect”s BIM model, he creates a simplified BIM model that contains the key elements that are required for the energy analysis such as simplified walls and floors, room bounding elements, complete volumes, and window frames and curtain walls. He exports the simplified model as a Green Building XML (gbXML) file. gbXML provides an industry standard schema for transferring building properties stored in 3D BIM models to energy performance analysis applications.

The energy analysis uses the geographical location of the building and the local environmental conditions to conduct thermal, lighting and airflow simulations to compute and estimate how much energy the building will consume in a year and test different design options (insulation, glazing, natural daylight, wind simulation and ventilation) to identify best possible solutions, compare lowcarbon technologies, and draw conclusions on energy use, CO2 emissions, occupant comfort, light levels, airflow and LEED certification level. By conducting energy analyses and testing alternative options, it is often possible to reduce annual energy consumption and power bills by 40%. As an added benefit, in Ontario, reducing the expected electric power usage of a new building generates an immediate payback at a rate of USD 400 to USD 800 per kW from the Ontario Power Authority”s High Performance New Construction (HPNC) program.

Summary
In the backdrop of global warming, the increasing demand for electric power is being increasingly met by alternative fuels and more importantly by optimising energy efficiency. In many jurisdictions, energy efficiency provides the least expensive alternative fuel. Buildings represent around 40% of the total primary energy consumption in many of the world”s advanced countries and increasing the energy efficiency of buildings has become a global priority. The convergence of 3D building information modeling (BIM), geospatial and energy modeling enables designers to reduce the energy footprint of existing structures, including even historic buildings, as well as design new, highly energy-efficient structures.

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