Whole Building Simulation is not further a complex process with Revit

This article is about my experience in Revit System analysis for whole building simulation in Sri Lanka.

#autodesk #revit

Recently, I could contribute for an ongoing Green Building research done by a Sri Lankan university. In the process their intention was to find-out impact on shading devices for annual building energy consumption in different regions.

We set two variables; Length of the shading device, Region of the building

I used Autodesk Revit 2020 for modelling of a typical Sri Lankan building as shown in the image. In built system analysis option was used to get output results.

Thermal transmittance (U value) is an important factor in energy simulation. In the material properties thermal values (Resistance -R which is the reciprocal of U ie R=1/U) were adjusted for roof, walls and default values were used for ground floor slab,windows and doors. Since main intention of this study was to compare different scenarios significant of the values are less important.

If you want to change U value in an element, you need to change thermal resistance (R) value in Material properties"

Advance Energy settings in Revit should be carefully studied to understand how input parameters can work. There are plenty of resources by Autodesk itself I followed during the study. Here is an example below,

Some Tips I learnt :

Pros:

1. Most of the other energy simulation software ( Design Builder, eQuest) need to rebuild a model from AutoCAD or by scratch. But Architect's Revit model can be used and seamless data transfer with updates on the original model.
2. Less complex environment in giving input parameters for energy model and pre loaded occupancy schedules, ASHRAE complying parameters (ex : Typical energy demand values - lighting, miscellaneous equipment etc)
3. Revit system analysis uses world wide accepted Energy Plus engine with the help of open studio.
4. Once you created the energy model you can check it visually to understand eny geometric errors occurred while modelling process.

Analytical Surfaces (No need to be watertight to have desirable energy model)

Analytical Spaces which is defined based on building type in advanced settings. This can be overridden by adding spaces and zones.

Cons:

1. There was a serious problem with weather station input for system analysis. Even though the workflow suggest to give Location data from Map service in the software it only take single weather station ; [Colombo Bandaranaike Intl AP WP LKA ISD-TMYx WMO#=434500] for any city. This is not reasonable for cities like Nuwara Eliya, Jaffna which have different climates to Colombo. However I noticed that Insight feature which uses online simulation through Green Building Studio take the weather input correctly.
2. Output report is not customizable such that you get a report with all inputs and outputs.
3. You cannot obtain outputs like indoor temperature fluctuation.

System analysis is an offline method of building simulation

From this experience, I can conclude Revit system analysis itself is not a better option to have outputs of whole building simulation. There are two main options ;

1. Use integration of Insight for have better outouts especially for Energy Use Intensity (EUI) and benchmarking different models
2. Introduce customized workflows to Revit system analysis since scripts are open and written in Ruby Language!

Let's meet in another article.