In order to ascertain the extent to which building upgrades, from fabric to HVAC, affect various building’s energy use the group used 2 approaches to simulation:
The first was to use SBEM, the BRE program that utilises the National Calculation Method to calculate a building’s overall energy consumption and carbon footprint then compares this to a “nominal” (benchmark) building. SBEM is an industry standard tool that allows flexibility in exploring building upgrades for carbon abatement.
The second was to use dynamic simulation to get a more comprehensive understanding of the dynamic relationship between various energy upgrades. For this, the software ESP-r was selected for reasons detailed below.
SBEM is a software developed by BRE for the Department for Communities and Local Government. It is an industry standard tool that uses the National Calculation Method (NCM) to calculate energy use in buildings (BRE, 2016).
SBEM is user friendly and, while inputting the data is time consuming, building upgrades are simple to implement. The outputs aren’t as detailed as ESP-r (giving monthly rather than half hourly data) but the relative ease of inputting detailed information about the building construction and systems makes it a valuable tool for comparing results. Where ESP-r gives detail, SBEM gives breadth.
This software tool has been used to obtain simplified energy models and energy savings from the different fabric upgrades implemented in selected buildings on campus.
In order to understand the transient nature and interactions between upgrades in fabric, changes in occupancy levels and casual gains from changing light fittings it was necessary to create simple models of select buildings across the campus.
These models complement the SBEM models where they explore the same changes (for example fabric upgrades) and add a layer of understanding in areas that SBEM is unable to calculate energy savings (for example changing set points or increasing occupancy).
Several dynamic simulation softwares were reviewed at a high level considering the following factors:
• Availability - whether the software is free, compatibility with operating systems etc.
• Usability - how accessible the software is to group members in terms of understanding and building a model.
• Suitability - can the software produce the required outputs i.e. allow sufficient detail of inputs and give results that enable investigation into energy saving potentials of the desired technologies?
Softwares considered included MatLab, Simulink, Modelica, EnergyPlan and ESP-r.
ESP-r most comfortably fit the selection criteria. Although the user interface can be challenging at times and every input must be entered manually it is a powerful software that can produce results in a level of detail enabling a depth of understanding into the driving forces behind energy consumption. There is also some experience in using the software within the group from a modelling module in the winter semester of 2015.
BRE (2016) SBEM: Simplified Building Energy Model [webpage] Available at: https://www.bre.co.uk/page.jsp?id=706 (Accessed: 30 April 2016)