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AECbytes Product Review (February 11, 2010)

Graphisoft EcoDesigner

Product Summary

EcoDesigner is an ArchiCAD plugin that allows simulation of the energy performance of a building to be analyzed within the ArchiCAD environment. It is based upon the VIPCore calculation engine, developed by Swedish company Strusoft.

Pros: Interface between ArchiCAD and EcoDesigner is relatively seamless; intuitive interface makes it quick and easy to enter the required material properties and operational data for the building; analysis results are presented as a succinct report that provides a clear understanding of the building’s likely carbon footprint and energy consumption.

Cons: Not intended to be a detailed analysis tool, relying on default parameters and values to speed up the calculation process; interface is slightly biased towards colder climates; powerful customization options within the program appear to be largely under-utilized.

Price: $645 for a single license of the EcoDesigner plugin for ArchiCAD 13; current ArchiPLUS subscriber discounted price is $275; free educational version for students.

Sid Thoo
Director, Architecture.collective

Developed by Graphisoft, EcoDesigner is a plugin that allows the energy efficiency performance of a building model to be analyzed within the ArchiCAD environment. It is a relatively new plugin, launched at the AIA 2009 Convention alongside version 12 of ArchiCAD. At the core of EcoDesigner is the VIPCorecalculation engine, developed by Swedish company Strusoft. This is the same engine that is used by Strusoft’s standalone analysis program VIP-Energy, and is certified in accordance with recognized analysis standards, such as the ANSI/ASHRAE BESTEST Standard 140-2001.

As both a technologist and an architect with a passion for energy efficiency and sustainability, I have been particularly interested in evaluating EcoDesigner. In some ways it represents the “holy grail” of building performance software, because of its ability to perform integrated analysis within the BIM model itself. Previously I have written about the various methodologies for transferring data between BIM applications and analysis programs, and the common pitfalls encountered (see my AECbytes article, Interoperability and Sustainable Design). This was prior to the introduction of EcoDesigner.  

The interface between ArchiCAD and EcoDesigner is seamless; the intuitive interface makes it quick and easy to enter the required material properties and operational data for the building in order to analyze building performance. Analysis results are presented as a succinct report that provides a clear understanding of the building’s likely carbon footprint and energy consumption. It should be kept in mind that EcoDesigner is not intended as a detailed analysis tool. It relies on default parameters and values to speed up the calculation process. Its interface is slightly biased towards colder climates, while powerful customization options within the program appear to be largely under-utilized.

As I became more familiar with the software, the following workflow seemed to be the most intuitive, which differs slightly from that recommended in the User Guide:

  1. Model Creation
  2. Automatic Model Analysis
  3. Location and Function Definition
  4. Structures and Model Review
  5. Additional Calculation Inputs (Openings, MEP Systems and Energy)
  6. Evaluation

Let’s look at each one of these steps in more detail.

Model Creation

Obviously, you need some kind of building model before EcoDesigner can be used. The example I am using here (see Figure 1) is an actual project from our office, a luxury house located in Perth, Western Australia. This model has been developed to the end of the detailed design stage, however you can use EcoDesigner as long as you have modeled at least the building envelope and any significant internal structures.


Figure 1. The sample project used to test EcoDesigner.

The other important point on model creation is the methodology you use for creating your ArchiCAD model. In order to ensure accurate energy analysis results, geometry tools should be used for their intended purpose (for example, Wall Tool for walls, Slab Tool for slabs, etc.), fills should be applied consistently to building elements, and structures should be classifiable as either internal or external (so, for example, a slab that is both should be split into two separate objects). If the nature of your project requires the use of standard geometry tools in unconventional ways, it may be necessary to create a simplified model for the purposes of EcoDesigner.

Automatic Model Analysis

The EcoDesigner plugin can be invoked from the Design > Design Extras menu. Upon execution, EcoDesigner performs a preliminary analysis of the building geometry, after which the following dialog box is displayed.


Figure 2. The Model Analysis dialog.

This is a brief summary of the structures that EcoDesigner is able to automatically identify in your model. Later, you’ll get the opportunity to review the model in more detail, and make changes as necessary.

Location and Function Definition

The main EcoDesigner window, shown in Figure 3, is made up of fours tabs—Location & Function, Structures, Openings, and MEP Systems & Energy. Details regarding each of these aspects of your building need to be provided in order for EcoDesigner to produce valid analysis results.

The Location & Function tab allows you to configure the overall parameters for the project, such as the location and orientation of the building. The option, Grade level to project zero sets the floor level of the building in relation to the surrounding site; the Wind Protection and Surroundings options can be used to configure the contextual environment. All these settings will have an impact on the overall energy analysis results.


Figure 3. The main EcoDesigner dialog.

The Façade Shadings button opens the dialog box shown in Figure 4. Rather than calculate detailed shading masks, here EcoDesigner makes some general assumptions about overshadowing of the building. The advantage of this is that calculation time is significantly reduced; however, given that the position of the sun varies considerably throughout the day and year, this speed is at the expense of a potentially more accurate result.



Figure 4.
The Façade Shadings dialog.

The second column of the Location and Function tab, shown in Figure 3, defines the occupancy profile for the building—this determines the target temperature and heat gain throughout the day. Buildings with multiple functions can be defined by clicking on the More functions button. Again, being a conceptual analysis tool, the pre-defined temperature and heat gain profiles should be adequate to cover most functional building types. However, it is possible to define fully customized temperature and heat gain profiles, as we will see later.

Structures and Model Review

The Structures tab of the EcoDesigner dialog, shown in Figure 5, is perhaps the most important one, as this is where it is possible to review the model analysis results previously calculated automatically. When you click the Model Review button on this tab, EcoDesigner switches back to a 3D Window view of the model, and then classifies the various structures as one of the following categories: Roofs, External Walls, Floors on Ground, Basement Walls, Basement Floors, and Interior Structures. Colors are based on settings from the Markup Tools palette, as shown in Figure 6.


Figure 5. The Structures tab of the EcoDesigner dialog.


Figure 6. The automatic classification of different elements of the building by EcoDesigner. The color settings used are also shown.

As you can see in Figure 6, EcoDesigner has done a fairly good job of correctly identifying the various building elements. However, a few elements have been marked up incorrectly, particularly where walls and slabs have been used to define external structures such as paving, garden beds, and balustrades. Using the EcoDesigner Model Review palette, these elements can be manually adjusted to minimize erroneous analysis results. The manually adjusted model is shown in Figure 7.


Figure 7. The manually adjusted model with all elements correctly classified.

Elements to be excluded from the analysis are left “as-is” and not marked up using the EcoDesigner Model Review palette. For example, in this particular project, the semi-basement level will be an unconditioned space. Note how roofs are defined using the EcoDesigner markup tools—roofs are essentially any horizontal structure that defines the building envelope. For example, in the top left-hand corner of the building shown in Figure 7, the floor of the semi-enclosed balcony is defined as a roof (colored in purple). In this instance, while this structure may be the floor of the balcony, it is also the roof of the enclosed space below.

Returning to the EcoDesigner window, the structures that make up the shell of the building need to be defined in terms of their thermal performance. Based on the Fill settings used in the model, EcoDesigner populates a list of the different types of materials used in the building shell. These are further itemized again based on their orientation, as shown in Figure 8.


Figure 8. The various structures that make up the building, itemized by their orientation.

At this point, it becomes apparent that it is beneficial to apply fills consistently while building your model. Not only is this a good standard practice when working in ArchiCAD regardless, it also means that the above structure list will be significantly shorter, meaning less time is required to assign thermal properties to each of the building structure elements.

By default, most of the building structure elements will be undefined, as indicated by the yellow triangle icon shown in Figure 8. To assign thermal properties, select the required row, and then click the button under the U-Value column. This displays the U-value Calculator dialog box, shown in Figure 9.


Figure 9. Assigning U-values to a building element.

Here you can assign thermal properties to the building structure, based on the fills used to define composite structures in the model. In this example, a cavity brick wall element has been selected, being composed of two 90mm skins of brickwork separated by a 50mm cavity (a very common construction method in Western Australia). The three thermal properties EcoDesigner requires are thermal conductivity, density and heat capacity. If you have these values from product literature or your own research, they can be entered manually. Alternatively, EcoDesigner provides an extensive database of materials from which you can select appropriate values, as shown in Figure 10.


Figure 10. Selecting thermal properties from the Material Catalog to calculate  U-values of composite building elements.

EcoDesigner stores the thermal properties with the fills defined in the ArchiCAD model, as shown in Figure 11, so this information can be used again for other building structure elements.


Figure 11. Thermal property assignments being saved for future re-use.

Once you have defined the thermal properties for each of the fills that define the composite structure, EcoDesigner calculates the U-Value (this can also be displayed as the reciprocal R-Value, also commonly used in product literature). If this value doesn’t quite correspond with what you would expect, you can adjust the External/Internal Heat Transfer Coefficient and Thermal Bridge Effect values manually (see Figure 12). These values are initially determined by EcoDesigner, but are intended to be altered to suit the particular circumstances of your project.


Figure 12. The U-Value (or R-Value) calculated for a building element.

After you have assigned thermal values to each of the building structure elements, there are a couple of other things that need to be configured under the Structures tab. For each item, select a surface finish from the drop-down list (see Figure 13), as well as infiltration. At the bottom of this tab, you can define what type of heat storage (thermal mass) applies to internal structures, as well as insulation to underground structures. You can also check that the floor area and building volume correspond with the actual spaces of your building. If there is a major discrepancy, you may need to complete the Model Review again to see if any structures have been overlooked. If the difference is minor, you can adjust the area and volume manually. EcoDesigner uses the values specified here in its calculations—it doesn’t calculate directly from the model geometry.


Figure 13. Setting additional properties of building elements in the Structures tab.

Additional Calculation Inputs

The Openings tab is very similar in layout to the Structures tab—a list is displayed of all openings based on orientation, where you can specify the performance values for each door and window grouping (see Figure 14). The values required include Shading, Percentage of Glazing, R-Value, Total Solar Transmission (also known as Solar Heat Gain Coefficient), and Infiltration for the door/window assembly.  Again, EcoDesigner provides a detailed library of performance values for different types of openings, as shown in Figure 15. However, it is interesting to note that the pre-defined library values appear to suit colder climates—for example, all of the listed window types assume double-glazing as a minimum standard.


Figure 14. Specifying the properties of the openings of the structure that will affect its energy performance.



Figure 15. Selecting opening properties from a catalog, if required.

The final tab is MEP Systems & Energy—here you can specify general information about the heating, cooling, ventilation and energy systems used in your building (see Figure 16). The Energy sources and costs button allows you to enter more detailed information regarding the types of energy available and the associated costs (e.g., electricity, gas, coal, etc.), while the Export to VIP-Energy allows you to save the analysis data for further analysis using the VIP-Energy software.


Figure 16. Specifying the properties of the MEP System and energy sources and costs.

For this 600 sq. m. residence, it took me around 20 minutes to enter all of the data required by EcoDesigner, and only minor changes to the model were required in order to rectify some discrepancies that became apparent during the Model Review stage. Unlike some building performance analysis programs that require tedious and laborious entry of data and material properties, this seems a reasonable amount of time, thanks to how EcoDesigner groups element types based on common fill properties and orientation. However, the potential drawback to this is that different door and window properties cannot be specified for individual assemblies that all face the same orientation.

Evaluation

Once all of the required information has been entered, the Start Evaluation button commences the calculation process, and then generates the evaluation report (see Figure 17). For this model, the calculation only takes a few seconds. Remember, the calculations performed by the VIP-Energy engine are not geometry-based and use generalized values, allowing for the significantly reduced calculation times.


Figure 17. The energy evaluation report generated by EcoDesigner for the sample project.  

The information contained in the report is fairly self-explanatory, and is presented in a clear and concise format. The terms used are defined in the EcoDesigner User Guide. Key project information is summarized at the top of the report, followed by a breakdown of energy consumption by source. Following this is an approximate carbon footprint, stated as the number of hectares of tropical forest required to offset carbon emissions each year. Concluding the report is a monthly energy balance graph, which plots energy emitted against energy supplied in order to maintain thermal equilibrium throughout the year. In this example, you can see that mechanical cooling is significant from Jan to March—this reflects the hottest months of the year in Perth, Western Australia. These energy balance results also infer that in its current form, the building does not perform well during hotter months, given the high demand for mechanical cooling.

So what do these results mean? This largely depends on the energy efficiency performance requirements and building regulations for the location of the project. However, the carbon footprint evaluation, if presented graphically (as shown in Figure 18), is the best illustration of this building’s current level of energy efficiency: To offset the emissions of this building, 8 tennis courts, or the equivalent of 14 times the building’s footprint in tropical forest would be required!


Figure 18. Graphical depiction of the carbon footprint evaluation of the sample project.

While these initial results do not appear very promising, here is where the value of an analysis tool such as EcoDesigner becomes apparent. Because we have gained valuable feedback on the building performance in the early design stages, and because of its tight integration with ArchiCAD, it is easy to start manipulating the model to see what can be done to improve the building’s performance. For example, changing the external wall construction and material properties to structural insulated panels and selecting high performance glazing for window assemblies results in a reduction from 40 tonnes to 28 tonnes of CO2—we can reduce the building’s carbon footprint by two tennis courts of tropical forest (see Figure 19). This performance improvement is corroborated if you look at the scale bar for the Monthly Energy Balance graph—the peak values are considerably reduced.


Figure 19. The revised evaluation report generated by EcoDesigner after making changes to the design to improve performance.  

Further improvements can be gained by manipulating the building’s energy consumption. Specifying natural gas for a larger percentage of heating in the building (as shown in Figure 20) reduces the carbon footprint by a further 6 tonnes per year, “losing” another two tennis courts. For cooling, if natural cooling is selected instead of mechanical, this would lose another tennis court. Of course, the effectiveness of the building design to allow for natural cooling would need to be evaluated independently.


Figure 20. Increasing the percentage of natural gas as the energy source for the building to reduce its carbon footprint.  

If electricity for the building is supplied predominantly from solar energy, the building’s footprint becomes almost negligible—only half a tennis court of tropical forest would be required to offset emissions. (Of course, solar panels are expensive, so improvements to the building’s performance should be considered first and foremost.) At this point, what would be really useful is if the solar panels section could be used to determine the area of panels required if the building were to generate its own electricity. Unfortunately, this section can only be used for determining heating, hot water, or fresh air energy requirements.

As can be seen, with some simple adjustments to the model and the operational parameters for the building, it is possible to dramatically improve the building’s energy efficiency. With further manipulation of the design model, additional emissions reductions could be achieved.

Analysis and Conclusions

For architects looking to gain a valuable snapshot into the environmental performance of a proposed building design during the early design stages of a project, EcoDesigner is a valuable design tool, particularly when used as part of an iterative design process. The near-seamless integration with ArchiCAD and speed at which EcoDesigner is able to generate building performance results makes it possible for you to explore different design and operational parameters to see how the building’s performance can be improved.

Of course, it is important to recognize that EcoDesigner is not intended to be a comprehensive building performance analysis tool—its results are generally based on default values, parameters or assumptions. For example, EcoDesigner does not calculate accurate shading masks for the building envelope, instead relying on one of three default values: plain, average or complex. It would be unreasonable to expect even the complex option to be able to accurately replicate the performance of a façade designed to self-shade, for instance. EcoDesigner is certainly not intended as an alternative to more sophisticated analysis programs such as IES, DesignBuilder, or Ecotect Analysis. The fact that initial EcoDesigner performance data can be exported to VIP-Energy for further analysis is testament that it is intended as a complementary analysis tool.

Being based on the VIP-Energy calculation engine, which originates from Sweden, one minor criticism is that EcoDesigner seems more biased towards evaluating building performance in colder climates. For example, when specifying energy sources and costs, an option is given for heating but not for cooling, while systems such as air to air heat recovery and heat pumps are not particularly relevant for buildings located in temperate and desert climates. While the software is still more than capable of analyzing a building located in any type of climate, it would be valuable if the interface were redesigned slightly to remove this apparent bias.

Perhaps the biggest criticism of EcoDesigner is not to do with the software itself, but with its largely unknown potential for customization. In addition to the PDF User Guide that ships with EcoDesigner, Miklos Sved (EcoDesigner Product Manager for Graphisoft) has written an advanced user guide, which provides detailed information on EcoDesigner customization and how to address certain modeling issues. (This document can be downloaded here.) Using intuitive XML formatting, users can easily create customized weather, operational profiles, and building materials data for use with EcoDesigner, as shown in Figure 21. It would be far more useful if this document were included with the product, rather than users having to hunt for it themselves on the Internet.


Figure 21. The ability to customize EcoDesigner using XML scripting.

In summary, as long as it is understood that EcoDesigner is intended a quick, conceptual analysis tool, it is a valuable plugin that should be considered as mandatory for all ArchiCAD users who are serious about designing more energy efficient and sustainable buildings. With some minor interface changes, and greater awareness of its customization options, EcoDesigner has the potential to become a critical part of the BIM workflow for those using ArchiCAD.

About the Author

Sid Thoo is an architect and director of architecture.collective, a practice that specializes in design and consulting for eco-effective and energy-efficient buildings. His son Alexander was born last year, and the family is doing just great. He can be reached at sid@architecture.net.au.

 

 

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