Synopsis

This tutorial explains how to generate and interpret results for a hourly temperature graph using Ecotect.

Duration

You will need about 25 minutes to complete this tutorial.

Training and Accreditation

Successfully completing this tutorial fulfills one of the practical skills required for completing Level 1 of the Thermal Performance training module.

Resources Required

To complete this tutorial, you will need the SimpleThermalModel.eco file located in the Examples folder of your Ecotect installation.

Tutorial

1. Open the SimpleThermalModel.eco file in Ecotect. The model consists of three simple zones with various window openings. Go to the Calculate»Thermal Analysis... menu item. The Thermal Analysis calculation wizard appears. Choose the Temperatures radio option and the click Next.
   

   Start the Thermal Analysis wizard.
2. On the next screen of the wizard, select the Hourly Temperatures radio option. There's no need to select the Show Losses and Gains in the Same Graph checkbox option - we'll cover gains and losses in the next tutorial. Click Next.
   

   Select Hourly Temperatures, but leave Show Losses and Gains in the Same Graph unchecked.
3. Select the day that you wish to calculate hourly temperatures for. You can do this manually, or click the Search Weather Data button to use pre-defined days, such as Hottest Day (Average) (if you haven't already set the location for your project, you will be prompted to load climate data before this context menu appears). Important Note: the orientation of your model will also effect the results of the hourly temperature graph, so make sure you have the correct north orientation for your project before proceeding.
   

   Choose the day/s to calculate.
4. Click Ok to calculate the hourly temperature graph, similar to the following screenshot (you may be prompted to recalculate interzonal adjacencies first - click Yes). Let's now have a look at the legend in order to interpret the results.
   

   The Hourly Temperature graph.
5. The dashed blue line represents the outside temperature, as derived from the weather data file loaded previously. The other coloured lines represent the temperature graph for the various zones in your model - the colours correspond with the colours used in the Zone Management dialogue box.
6. To highlight the results of a specific zone, use the Highlight Zone section below the graph to select the zone of interest. Not only does Ecotect highlight the graph for the selected zone bold, but it also overlays colour gradient bands to indicate relative comfort (ideally, the graph should fall within the white band of the colour gradient). Note how all of the zones currently fall in the too warm comfort band.
   

   Highlight a zone to see comfort bands.
7. The dashed and dotted orange lines represent Beam and Diffuse solar radiation, measured in W/m². Beam Solar refers to the direct component of radiation from the Sun itself, whereas Diffuse Solar refers to radiation that occurs due to reflections from clouds, moisture vapour and other atmospheric particles. All of this data is derived from the load climate data file. Note that for this location, the majority of solar gains are due to direct beam solar radiation, peaking at just under 1kW around noon for the selected day. Also, the sharp drop in direct solar radiation between 6pm and 7pm corresponds with a similar drop in the temperature of Zone 2, which suggests that a west facing window in this zone may be allowing undesirable heat gain into this zone.
8. Wind speed is indicated by the green dashed line, and is derived from the loaded climate data file. For the purposes of this graph, wind speed is shown to indicate its relative influence upon the temperature patterns within zones being analysed, and so is not plotted in relation to either of the Y-axes for temperature or energy. Note how an increase in relative wind speed after 8pm seems to coincide with a general decrease in zone temperature, but that a wind speed increase between 6am to 2pm does not have a similar effect (zone temperatures still seem to rise proportionally). This pattern seems to suggest that wind speed does not seem to have a significant impact upon the temperature of the internal spaces.

Interpreting and working with the results

The next section of the tutorial looks at how changing aspects of the model will impact upon the hour temperature graph.

1. In the Thermal Calculation section of the Thermal Analysis tab, there are two checkboxes that allow you to isolate either inter-zonal gains and/or solar radiation from the hourly temperature profile. Uncheck Inter-Zonal Gains and then click the Calculate button to regenerate the graph. Note there is very little difference to the temperature profiles for each of the zones, indicating that inter-zonal gains do not contribute greatly to the internal temperature of the zones. Conversely, if uncheck Solar Radiation instead, this has a significant effect on the internal temperatures of each of the zones, suggesting that the design needs to be modified so as to reduce temperature gains caused by solar radiation.
   

   You can isolate interzonal gains and solar radiation respectively from the hourly temperature graph.
2. Return to the 3D editor, and try changing all of the zone wall materials from Brick Timber Frame to Reverse Brick Veneer R2.0. Click on the Analysis tab and then recalculate the graph. Note how this change of wall material reduces the internal temperature of the zones by around 2°C. Simply reversing the brick veneer construction significantly improves the comfort of the building.
   

   Try changing the external walls to reverse brick veneer.
3. Select the ceilings over all of the zones - they have been assigned the roof material of Clay Tiled Roof. Try changing this to Metal Deck Insulated. Recalculate the temperature graph, and you will see a significant reduction in the internal temperature of all zones, especially between the hours of 11am and 6pm.
   

   Changing the roof material to Metal Deck Insulated further reduces internal temperatures.
4. Look at the beam solar radiation line (yellow dashed) in relation to Zone 2 - the noticeable rise between 9 and 12am is not directly associated with a corresponding pattern in internal temperature, whereas the sudden fall in direct solar radiation between 6 and 7pm is. This also coincides with a drop in wind speed (green dashed), however fluctuations earlier in the day did not noticeably affect temperatures so, therefore it is unlikely that this late afternoon fall was wind-induced. Rather, it is more likely that the west facing window in Zone 2 is the cause of this drop. To verify this. try deleting this window, and then recalculate the temperature graph (Click Yes to recalculate interzonal adjacencies) - you will notice that this 'smooths out' the temperature profile for Zone 2.
   

   Delete this window, and then recalculate the hourly temperature graph.
   For a laugh, try adding a window to the south elevation instead, and recalculate the graph to see the effect of this.

As can be seen, relatively minor changes to the model and its materials can have a significant on the internal temperature of a zone. Using a hourly temperature graph is one method that allows you as the designer to quantify and validate changes that will have the optimum desirable outcomes for your proposed design.