CAD User Online Article Archive

Review

EcoDesigner

From CAD User AEC Magazine Vol 22 No 7 - JULY/AUGUST 2009

Graphisoft's EcoDesigner has a neat twist with its energy evaluation results, says David Chadwick. As well as showing you how your proposed building will perform, it will also graphically illustrate how many hectares of rainforest will be needed to absorb the carbon dioxide you will be churning out

It must be something to do with the weather. Here we are in the middle of a God-awful July, with the rain sweeping across the country in seemingly endless bands, and we have the release of another building energy evaluation tool, adding its own ingenious twist to the need to address our spiralling energy consumption. You can almost hear the subtext between the downpours - 'If you don't sort this out then there's plenty more rain to come!'

Graphisoft's EcoDesigner has been designed for use by architects as an integrated, easy-to-use, energy evaluation tool. It's built into Graphisoft's ArchiCAD 12, of course, and is currently being released onto the market. The aim of the software is to allow architects to control the energy consumption of buildings, and according to Graphisoft sets new standards in sustainable design.

It has also been designed to be used at all stages of the design process - from initial concept, up to the construction phase, supplying or sourcing the information required by architects to perform building energy analyses throughout. Being quick and easy to use will encourage repeated analysis and experimentation with alternative technologies and methods to provide optimum design solutions.

The alternative is to perform traditional building energy evaluations, which are normally undertaken by outside professionals, and only when the building design is well advanced. Any substantial flaws in the design revealed at that stage are well nigh irreversible - or extremely expensive to change.

ECODESIGNER

EcoDesigner is used, therefore, to measure and control the energy consumption or production of buildings, allowing designers to make informed decisions early on in the design process. According to National Geographic magazine, 80% of decisions about sustainability are made in the conceptual design phase anyway. The tool is part of Graphisoft's Virtual Building or Building information Modelling suite, and leverages the parametric modelling and data handling capabilities of the software. It can be used to compare energy consumption and monthly energy balances and can be set up to run 'one-click' energy evaluations at any point in the design process.

ECODESIGNER WORKFLOW

The software goes through three separate phases - analyse and calculate, and then culminating in a summary of energy consumption results and a carbon footprint

calculation, and a series of diagrams showing the monthly energy balance.

Perhaps analyse is the wrong term to use here, as Graphisoft's analysis phase equates to the setting up of the structure for EcoDesigner's energy consumption calculations. The analysis they refer to is the investigation of the structure, prior to applying the properties required for the calculation.

EcoDesigner uses an automated structure mark-up routine, where rooms and spaces are categorised and assigned with properties and materials. The results are displayed in colour on 2D floorplans, and in 3D, for easier visualisation of the area under review. Once the structure model has been downloaded and marked-
up the results can be fine-tuned manually using the Model Review Palette.

CALCULATION DATA INPUT

A variety of data needs to be added to those already inherent in the model before

Monthly Energy BalanceEnergy Balance Evaluation Report the calculations can take place. Some of these relate to the building type - heavy, medium or light weight - and it's orientation with regard to whether it faces North, South or otherwise, and whether it has any wind protection, or the amount of shading from adjacent properties, parts of its own design or trees for each of the structures facades.

A good deal of information is sourced from online weather databases or the software's own built-in database, supplying, once the geographical coordinates have been entered, local weather data - air temperature, relative humidity, wind speeds and solar radiance - based on averages from the last so many years.

Inside the structures, you can specify internal heat gains and a required internal temperature. Each specified activity has predefined day by day thermal profiles for different types of building occupation offices, residential buildings, hospitals and various industries.

A U-value calculation is undertaken of the heat transmission of the building envelope structures at every hour throughout a year, using an accurate dynamic calculation algorithm. This takes into account the material properties of the structure, such as the thickness and type of plaster wall coatings, concrete flooring and so on. The thermal properties of openings can also be attached, using data from built-in opening catalogues, or entered manually where applicable.

I must stress that these preliminary calculations are not considered to be the calculation phase of EcoDesigner, but merely a means of providing an environment in which the full analysis can be undertaken.

MEP SYSTEMS & ENERGY

And, of course, there are all of the heating, ventilation, energy sources and other technical gizmos that supplement the natural structural environment. All information about proposed MEP systems has to be provided for the software, and with it any ventilation systems and types, air-to-air energy recovery systems, heat pump info, solar panel set-ups and target performance levels, hot water generators and cooling and air conditioning systems. Where these will be set to run at minimum or maximum temperatures, that information will have to be included as well.

The end result is a complete environmental model of the structure, together with a mass of data about local weather and the building's energy systems. And, if you throw in the local price for the types of energy proposed, and set up the proportions for each, you can even calculate the carbon footprint of the project.

CALCULATE -AT LAST!

Once you are satisfied that all parts of a structure have been marked up or used in the calculation, and that all relevant data has been entered, you are faced with the ultimate critical decision! That is to press the blue (should be green) Start Estimation button.

This will start the StruSoft VIPCore Calculation Engine, which will perform the dynamic energy analysis, turning out the results in XML format. StruSoft is part of a whole range of tools for the design and analysis of structures, developed by UK company AceCAD, a leader in this particular field.

EVALUATION RESULTS

Out of the end of the calculation engine should pop the Energy Balance Evaluation report, which provides a summarised energy consumption, calculated according to consumption type (heating, cooling, lighting, usage) and prime energy usage (gas, coal, oil, nuclear energy, electricity). The entire building’s average U value can also be identified. The results are available as pie charts, or in numeric tables.

The carbon footprint information shows carbon dioxide emissions that will result from the building's operations over the course of a year. As a neat twist, the area of the tropical forest that is needed to absorb this amount of carbon dioxide is included for comparison - just to make you feel guilty enough to go back into the design and work out how to get your carbon emissions down even lower!

The Monthly Energy Balance provides a bar chart showing the amount of energy the building will emit monthly, together with the building's supplied energy - and where it comes from - its own heat sources, solar gain, recovered energy and so on.

The Building Energy Evaluation Report can also be made available, instantly, in PDF format.

CONCLUSION

The aim is to repeatedly re-visit your designs to calculate the optimum solution that will satisfy the buildings functions and at the same time, minimise energy consumption and carbon emissions. EcoDesigner puts that capability in the hands of the architect in a simple and easy-to-use solution. www.graphisoft.com

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