You may find it useful to read this in conjunction with the tutorial on Input Data for Thermal Simulation.
Ecotect is a very flexible tool which can be used to provide a variety of types of design assistance. The approach in this tutorial is to look at its use as a classical thermal simulator. Other tutorials will add further detail to its use in this capacity and also look at its other uses.
The tutorial Input Data for Thermal Simulation looks at the different categories of data to be entered into a thermal simulator and here we look at applying these rules.
Ecotect has an extensive help menu, but up to the release 4.0 a good but incomplete set of tutorials. You should make yourself familiar with the help menu and use it to extend your knowledge. You can download the software from the Square One website but you will not be able to save any work and you will be limited to 60 minutes use in any one session. However, you can load files of projects created with a registered copy of the software and learn about one aspect without having to enter all the data again.
As with most modern software, the user interface permits two main ways of actioning the software: A traditional pop-up menu plus separate toolbars. For ease of writing, I have chosen in most cases to describe the traditional method. Menu instructions and buttons in the software appear in italics.
1. Define Location and Load Climate Data
Model -> Date/Time/Location: Ecotect has a limited set of weather files. Enter Latitude, Longitude and Time Zone. Click on the Map button if any of these are unknown. More accurate values may be found using Meteonorm (the Find button in Version 4.0 appears to connect to a database of only Australian locations).
Load Climate Data to load a WEAther data file. Note that this loads in the following parameters.
Though all these parameters may be available to Ecotect, it does not mean that they are all used by the software. Other Square One software uses these weather files.
Other parameters which can be set in this dialogue box:
The Date/Time input is used when modelling of a specific day is selected. This is useful for some of the design functions, such as sizing of shading devices.
Orientation: When you construct your physical building model, these will be aligned with a 3-dimensional grid. The orientation of each facade being determined by its position relative to the grid. The orientation button allows you to rotate the model relative to compass points without having to alter the model on the drawing grid. Orientation can be set negative and positive values. Take care to rotate it correctly, check the result of this.
Terrain is used to modify the wind data.
2. Create 3 dimensional representation of the building
We are simply going to create a rectangular building with flat roof of no eaves, and a single window in the northern wall. You may find it useful before creating more complex structures to follow the official tutorials for Simple House, Classroom and Auditorium.
2.1 Set the drawing grid
Click on the Grid tab. All dimensions should be in millimetres. As we are presently drawing something simple we can set the grid spacing high (1m ie 1000mm, say). The grid extents should be sufficient for your present needs. Ensure that Display North Point is ticked.
File->User Preferences click on tab Cursor Snap. Ecotect employs various drawing aids in the way of helping to position the cursor to make drawing easier. These will be most useful when drawing more complex buildings. Set the Grid Snap to 1000mm. click on the modelling tab and set the default zone height to 2700 (2.7m), all subsequent spaces will have this floor-ceiling height.
2.2 Draw the building
Your building is rectangular in plan with East and West facing facades of 5m width and North-South facades 8m in width.
Draw->Zone, cross-lines will appear on the drawing canvas. Click at a point on the grid close to the origin (adjacent to North arrow), move North 5m and click to locate the base of the West wall. Move down (East) 8m and click to locate the base of the North wall. Complete the final corner in the same way. Press ESCape to complete the zone.
You are about to place a window in the north wall. This will be easier if you rotate the canvas, so that this wall appears in elevation. The cursor keys (arrows) facilitate this. Hold down the CTRL key to Pan. Hold down the SHIFT key to fine tune.
Click in the North wall so that only this object is selected. If you have problems selecting it but have selected an adjacent surface press the space bar to toggle between different surfaces. Draw->Window. You are to draw a window 1m high, with cill 1m above the floor and width 6m in the centre of the wall. This is drawn in the same way as you defined the corners of the zone. If you make any errors whilst drawing and have drawn 2 corners or less (obviously, you need at least 3 to draw any surface) you can simply ESCape the process. If you have drawn more than 2 corners ESCape to stop drawing then select the window and press the Delete key.
2.1 Set construction materials
Calculate->Zone Volumes. Ecotect will calculate Surface Areas automatically but not volumes.
You now have 7 surfaces: 4 walls, 1 roof, 1 ceiling and 1 window.
There appear to be various ways of defining the construction materials/layers for these surfaces. You can also redefine a wall as a ceiling or make other unusual assignments (you can easily do this by accident). This simple building is to use the same materials for all its walls. Thus we can set up these constructions by Select->By Element->Walls followed by Modify->Object Properties. Select Double Brick Plastered in Primary Material panel.
Apply the same sequence for Ceiling (Plaster Ceiling), Floor (Ground) and Window (Heat Absorb 10mm TF). Note that these materials have been selected purely because it appeared that many of the other materials in the database had not actually been defined.
You may notice that the Selection Information panel shows for all surfaces an exposed area of 0.0m2. This will mean that none of these surfaces will receive solar radiation. To assign these correctly you need to Calculate->Inter-Zonal Adjacencies Notice that the software detects that the zone has no roof and thus sets the ceiling as exposed to the external environment.
3. Internal Environment of the building
we need to define the internal heat gains ie details about occupancy, lighting, equipment use. These need timings of these are set according to schedules. We will create a simple schedule for a 5 day week.
Model->Schedule Editor. In the left hand panel type in the schedule name. Let's call it 5DayWeek. Select on the Monday tab and drag the mouse to Friday. Now in the right hand panel we can define the percentage of any total loads we define. We will set maximum use between 9am and 5pm with no use at any other time. One way to do this is to click on Value cell for 9am and type in 100. This represents 100% of the full load. Type this value into all the cells until 5pm. The graphical dsplay will show that the loads gradually increase from 8am to 9am, this could represent the workforce arriving gradually over this period, turning lights and equipment as they begin to settle for a 9am start. Similarly the period 5pm to 6pm is a gradual decrease in loads representing the workforce gradually leaving and turning off lighting and equipment. One these are set click on the Assign tab. Saturday and Sunday remain zero. Click on OK to save.
These schedules have no meaning unless we can apply them to a set of internal loads and occupancies.
Model->Zone Management. Make sure your zone is highlighted. We need to check that it is assigned as a Thermal zone (which is labelled with a T. If crossed out then select it to change. Click on the Air Conditioning tab. Check that no HVAC is defined. This would prevent examination of passive performance. Click on Occupancy tab. Set the number of people to 10 (say). Office workers will be sedentary. Set the schedule to 5day week. Set Heat Gains. Latent gains represent evaporation from heat source. These will not be significant for most equipment and so can be set to zero. Convective and Radiative heat gains are combined as Sensible heat gains. Set these to 20W/m2, say. Set schedule for heat gains as occupancy. Leave Air Change details. Click on OK.
Now we have all the inputs, we can calculate->thermal performance. We will examine the performance of a couple of single days. Ecotect can identify hottest and coldest days and we can examine these. The term hottest day can mean many things, it can be represented by the hottest recorded daytime temperature, the highest mean temperature or maximum solar radiation. The coldest day can have similar definitions. Glazing ratios and thermal mass will have the most influence on which of these represents the greatest problems. To calculate the internal temperatures when solar radiation is maximum, select Search data for hottest day(peak). Now click on recalculate and the expected temperature variation will be displayed. Investigate the other definitions of 'hottest' and 'coldest'.
To familiarise yourself with the procedure, repeat it. You can draw a different building, change the position/number of glazings, draw non-rectangular rooms (but only one for now) or any other parameters but keep it simple and only do the steps you have done here. We will look at more complex set-ups later. To speed up the process there are a set of short instructions, listing only the different steps.