Zones in ECOTECT are roughly equivalent to Layers in AutoCAD and Levels in Microstation. However, in addition to the normal use of layers to group related objects in a model, a zone in ECOTECT can also be taken to mean a room within a building - more specifically a single enclosed homogeneous volume of air.
These zones are referred to as Thermal Zones and are very important concept in ECOTECT when performing thermal analysis.
Proper Zoning is Not Always Critical
If a model is being built solely for shadow and lighting analysis, or for export to another analysis application, then its zones really don't need to define enclosed spaces and may be used in much the same way as layers and levels in other CAD tools. However, for thermal and acoustic calculations the proper definition of zones is critical, as it will determine the accuracy of the analysis. For more information, please see the Thermal Modelling topic.
Many Ways to Create a Zone
It is not necessary to create zones in any special way, such as always using the Zone Tool in the modelling toolbar. Any element can be moved between different zones at any time. Thus, it is relatively easy to zone up an imported CAD model - right-click in the Zone Management panel and choose the Create New Zone... command. Select the objects in the model to be included as part of the new zone, then select the Move Selected Objects To command in the same menu.
There are a number of important other aspects of zones that you should familiarise yourself with:
Thermal Zones Non-Thermal Zones The Outside Zone Interactions Between Zones The Current Zone The Roof Zone OpenGL Views
Thermal Zones
Any zone in the model can be defined as either a thermal or non-thermal zone. This can be done in the Zone Management dialog or in the Zone Management panel on the right hand side of the main application window. A thermal zone is indicated by a red letter T icon, as shown below.
A Thermal Zone is assumed to be an enclosed space within the building. As such it must be completely enclosed with planar objects forming its floors, walls, ceilings or roofs. There is no restriction on the number of different types of surface, as long as it is completely enclosed on all sides with sufficient geometry to allow its volume to be calculated.
As a conceptual test, imagine that the space itself were full of water. No matter how the zone is tilted or spun around, no water should be able to leak out. If the zone is partially open to the outside, then define that opening with a VOID object so that ECOTECT will know its there. For more detailed information on zones and zoning, refer to the Thermal Modelling topic.
The full enclosure of each individual zone is irrespective of whether it shares surfaces with other zones - ECOTECT automatically works out which surfaces overlap during the Inter-Zonal Adjacency calculation and assigns such objects their Alternate Material. For more details on how this is done and what it means, see the Double Counting help page.
This does mean that a lot of the geometry in a building will be duplicated on different zones. The following example shows a room and an area under a staircase. It clearly shows how the zones must be constructed in order for ECOTECT to properly determine adjacencies. Whilst this duplication may seem to be an unnecessary waste of memory, remember that ECOTECT is a conceptual tool whose models are subject to constant change and editing. Such a system allows you to shuffle zones around at will, quickly trying out different configurations without ever having to worry about reassigning and adjusting the materials of areas of overlapped geometry.
Non-Thermal Zones
Non-thermal zones do not appear in the selection lists of many calculations and do not participate in volume, temperature or heat load calculations. They are used to hold items such as construction lines, shading devices (explained later) and other non-participatory data. Their elements will provide shade for and reflect light onto other objects in other zones, but incident solar radiation and overshadowing calculations are not performed for them. No attempt is made to calculate their volume and the objects they contain will not have shading masks generated for them.
The Outside zone is always defined as non-thermal as it cannot have a volume (it is assumed be infinite) and its temperature is taken directly as the dry-bulb temperature in the current climate data file.
The Outside Zone
Whilst a model can contain any number of zones, it will always contain an Outside zone. This is automatically created within the model and cannot be removed or renamed. This zone should be used to store external objects such as fences, trees and site boundaries.
It is also a good idea to include external shading devices on this layer as well, so that they do not contribute thermally to any particular zone. If such a device were left as part of an thermal zone, any solar radiation collected by the shading device would be transferred into that zone, falsely increasing internal loads.
See the Non-Thermal Zones section above for information on using the Outside Zone to simulate Earth berms and underground building elements.
Interaction Between Zones
In order to determine the spatial relationships between different zones, ECOTECT performs an Inter-Zonal Adjacency calculation prior to any detailed thermal and acoustic analysis. This works out the areas of each material through which each zone will likely exchange heat, air, sound and potential overshadowing with other zones.
Thus, if two walls from different thermal zones are immediately adjacent to each other, then heat will flow will take place based on the overall thermal conductance of their alternate material and the temperature difference between the two zones. If the walls completely overlap, then the exposed area of each will be zero - meaning that they will not collect solar radiation or exchange heat with the outside. If they partially overlap, then ECOTECT will work out the relative areas in each condition.
However, to allow for special conditions such as earth berms or surfaces you wish to ignore, ECOTECT uses some special relationships between adjacent objects on thermal and non-thermal zones.
Earth Berms and Adjacent Objects on the Outside Zone
Any area of a surface on a thermal zone that is immediately adjacent to a surface on the Outside Zone are assumed to be underground. This way it is possible to consider the effects of an earth berm by simply drawing in the area of walls covered by the berm using planes on the Outside Zone. The diagram below illustrates a simple example during an inter-zonal adjacency calculation. In the model shown, objects on the thermal zone are shown in blue whilst the Outside Zone is shown in black. The red dotted area represents areas of adjacency.
Important Note: You will notice that the entire floor surface is also dotted, even though it is not adjacent to an object on the Outside Zone. This is because any object that sits on the ground plane (z = 0) is assumed to be adjacent to the ground. Similarly, any area of a surface that below the the ground is also assumed to be underground. The use of adjacent objects on the Outside Zone is only required if earth berm is not completely level or only affect part of the building. If it is completely flat, simply lower your building below the ground plane the appropriate amount.
Adiabatic Surfaces and Objects Adjacent to Non-Thermal Zones
There are occasions when you will want to totally ignore the heat flow though some objects. This is valid if you are modelling a single terrace house in a long row of exactly similar houses, as shown in the example below. It is relatively safe to assume that the temperatures in the houses on either side will be roughly the same as that in the modelled house, so the thermal transfer through these side walls is likely to be negligible compared to the losses and gains from outside. A similar condition occurs if you want to model a single floor in the middle of a high-rise building.
If you were to leave the side walls out of the model, ECOTECT would not know they were meant to be there so the zone volume calculations may fail and the internal thermal mass they would add to the space would be missing, as would their effects on mean radiant temperature in the space.
One option is to model the side walls as PARTITION elements - and in the case of the terrace house this would work well. However, for the multi-storey building, setting the floor and ceiling as partitions would mean that the space would have no FLOOR elements and hence a zero floor area. Thus, any internal gains (given in W/m2 of floor area) would not be properly assigned.
To overcome this, any object on a thermal zone that is immediately adjacent to an object on a non-thermal zone (except the Outside zone as explained above) is assumed to be adiabatic. This means that there is not net flow of heat through it in either direction - effectively simulating a material with exactly the same temperature on either side of it.
This way, the two transparent zone on each side of the example terrace house shown above could be located on the same non-thermal zone and the required effect would be achieved.
Important Note:The side zones in the above example have been made transparent for illustrative purposes only. In this particular case, it would not matter if they were assigned a transparent material because the surfaces they are adjacent to will have a zero exposed surface area so will not collect any solar radiation anyway and the side zones do not overshadow the thermal zone. However, if any part of the side zones projected out such that they did overshadow the thermal zone, then you would need to make them fully opaque to properly represent their shading effects.
Shading Devices Must be on a Non-Thermal Zone
Given that you can design a building of any shape or complexity, the geometric modeller cannot tell if any specific surface is inside or outside a particular zone (without inordinate calculation time). Thus, all exposed surfaces in a thermal zone will contribute fabric and solar gains to the enclosed space, with the exception of internal PARTITION objects. Thus, if you create a number of large external shades on a zone, ECOTECT will simply add any incident solar radiation that falls on them to the overall indirect solar load of that zone and include them as part of its surface area. Even if you make them PARTITION objects, they will still contribute additional internal thermal mass to the zone that isn't really there.
However, solar radiation falling on objects on the Outside Zone and on non-thermal zones is ignored. Thus, all external shading devices must belong to a non-thermal zone or to the Outside Zone. In the example below, the shading device belongs to a non-thermal red zone whilst the grey zone it is shading is completely separate and thermal.
The Current Zone
Within ECOTECT, there is always one zone set as current. This is the zone to which any newly added objects will belong. This is either the last zone added or the last zone set as current in the Zone Management dialog or Zone Management panel.
You can set a new zone as current in the following ways:
Double-clicking it in the Zone Management panel. Right-clicking in the Zone Management panel and choosing the Make Current menu item. Selecting an object and choosing the Make Selected Zone Current item in the main Model menu. Right-clicking a selected object in the 3D Editor and choosing the Make Selected Zone Current item in the Zone menu. Selecting the Zone Button in the left hand toolbar and drawing in a new zone. Opening the Zone Management dialog box and double-clicking a zone entry.
The current zone is displayed in the Zone Management panel as bold as well as in the Snap Settings toolbar at the top of the application window, as shown in the image immediately above.
The Roof Zone
A 'Roof Zone' is automatically created when you first add a Pitched Roof object. This zone has no special properties other than it is where all Pitched Roof Objects will automatically belong. By default, this zone is created with no occupancy or internal gains of its own.
If you have more than one building, you will need to manually create a new zone for the objects of each roof for each building and move the required objects to them. For information on creating and renaming zones, see the Zone Management dialog topic.
Even the Roof has a FLOOR
When a pitched roof is created, all elements are of type ROOF, except for the base-plane which is a FLOOR element. The base-plane is always the element that is adjacent to the CEILING element of the zone below. It may not seem to make sense describing the base-plane of a roof as type FLOOR, however it makes perfect sense to ECOTECT when it performs calculations. Instead of thinking of it as a FLOOR element in terms of construction, consider the word FLOOR to describe the fact that the plane is at the bottom of the zone.
OpenGL Views
An 'OpenGL Views' zone is also automatically created when you first add a Camera View object in the OpenGL Visualisation page. This zone is special in that, even if it is hidden or turned off, the camera views it contains will still be available in the OpenGL visualisation window. This is essentially to stop large numbers of cameras cluttering up the main 3D Editor view. If you have cameras on any other zone, turning them off will remove them from the OpenGL view list.