Energy Modelling Tool — Cheat Sheet
Quick-reference cheat sheet for the Energy Modelling Tool tool.
Published 27 May 2026
Energy Modelling Tool
Quick-reference companion for the free Portal tool
What This Tool Does
The Energy Modelling Tool is a powerful simulation platform designed specifically for South African architects to assess and optimize the energy performance of their building designs. It enables you to predict a building's energy consumption for heating, cooling, lighting, and ventilation, ensuring compliance with national energy efficiency regulations like SANS 10400-XA and SANS 204.
Use this tool from the early design stages to inform material selection, fenestration design, orientation, and shading strategies. It's crucial for projects aiming for green building certifications (e.g., Green Star SA) or simply striving for cost-effective, comfortable, and sustainable buildings. Anyone involved in architectural design, particularly those focusing on commercial, residential, or public sector projects in South Africa, will find this tool invaluable for data-driven decision-making and performance verification.
Step-by-Step Usage Guide
Begin by creating a new project. Input your project's location. For example, for a project in Johannesburg, enter "Johannesburg" or "26.2041° S, 28.0473° E". Select the appropriate climate zone (e.g., Zone 1 for Highveld regions like Johannesburg). This automatically loads relevant weather data.
Define your building's footprint, number of floors, and overall dimensions. Specify the orientation (e.g., "North" for the primary façade). The tool allows for simplified block modeling or importing basic geometry from CAD for more complex shapes.
Input your wall, roof, and floor construction details. Select from pre-defined South African material libraries or input custom U-values. For instance, an external wall might be "220mm brickwork + 50mm cavity + 13mm plaster" with an approximate U-value of 1.2 W/m²K.
Define all windows and doors. Specify their dimensions, orientation, and glazing properties. For typical South African commercial buildings, you might use: "Double Glazing, Low-E coating, Argon filled" with a U-value of 2.0 W/m²K and a Solar Heat Gain Coefficient (SHGC) of 0.4. Don't forget shading elements like overhangs or fins.
Set internal temperature setpoints (e.g., 22°C for heating, 24°C for cooling), occupancy schedules (e.g., "9 AM - 5 PM weekdays"), internal gains from lighting (e.g., 8 W/m²) and equipment (e.g., 10 W/m²). This reflects the building's operational profile.
Click "Run Simulation". The tool will process the data and generate reports detailing annual energy consumption (kWh/year), peak demand, and energy cost estimates. Analyse the results against SANS 10400-XA requirements or your project's performance targets. Identify areas for improvement based on the breakdown of energy use.
Common Scenarios & Expected Results
| Scenario | Key Input | Expected Output (Johannesburg, Office Building) |
|---|---|---|
| Baseline SANS 10400-XA Compliant | Single glazing (U=5.7, SHGC=0.7), Uninsulated cavity walls (U=1.8), Basic roof insulation (U=0.6) | Annual Energy Use: ~180-220 kWh/m²/year. Meets minimum SANS 10400-XA but with high heating/cooling loads. |
| Improved Glazing & Insulation | Double Glazing (Low-E, U=2.0, SHGC=0.4), Insulated cavity walls (U=0.8), Enhanced roof insulation (U=0.3) | Annual Energy Use: ~100-140 kWh/m²/year. Significant reduction in HVAC energy, improved thermal comfort. |
| Passive Design Optimised | Above + Optimal orientation, external shading, natural ventilation strategy, high thermal mass | Annual Energy Use: ~60-90 kWh/m²/year. Drastically reduced HVAC energy, potentially achieving Green Star SA ratings. |
| Over-glazed, Poor Orientation | Large, unshaded west-facing single-glazed windows, light roof construction, minimal insulation | Annual Energy Use: >250 kWh/m²/year. High peak cooling loads, thermal discomfort, non-compliant with SANS 10400-XA. |