Thermal Comfort Analysis Using CFD: South Africa Construction Project Case Study

How SuperDesignTech delivered a complete Computational Fluid Dynamics (CFD) based Thermal Comfort Analysis report for a major construction project in South Africa for a Fortune 500 client.

Executive Summary

Thermal comfort in a large building is not determined simply by the average room temperature shown on a thermostat. Occupants experience the combined effect of air temperature, air velocity, mean radiant temperature, humidity, clothing insulation and metabolic activity. In mechanically ventilated buildings, the location and type of air terminals, return-air strategy, internal heat loads, solar gains and architectural geometry can produce substantial spatial variations in the indoor environment.

For a major construction project in South Africa, SuperDesignTech was engaged to perform a detailed Thermal Comfort Analysis using Computational Fluid Dynamics. The objective was to assess the indoor airflow and thermal environment, identify potential areas of occupant discomfort and provide engineering evidence that could support HVAC and building-design decisions.

SuperDesignTech has been working on Thermal Comfort Analysis and advanced CFD applications since 2009. The South African project was handled through the company's global CFD engineering delivery team, combining building-flow modelling, heat-transfer analysis, HVAC representation and engineering post-processing.

Why Thermal Comfort Required CFD Analysis

Conventional load calculations are essential for HVAC design, but they do not by themselves describe the three-dimensional distribution of air velocity and temperature throughout a complex occupied space. A CFD model can resolve the interaction between supply air, recirculation, buoyancy, internal heat sources, envelope heat transfer and return-air paths.

In this project, the CFD Analysis was therefore used as a spatial engineering diagnostic. Instead of asking only whether the building had sufficient nominal cooling capacity, the analysis investigated where the air moved, how temperatures developed, and which occupied regions could experience an undesirable thermal environment.

Project Engineering Scope

The analysis workflow covered the following major areas:

• Three-dimensional preparation of the building and occupied-zone geometry.
• Representation of HVAC supply and return-air locations.
• Definition of relevant internal heat gains from occupants, lighting and equipment.
• Representation of envelope and heat-transfer boundary conditions appropriate to the project.
• Airflow and heat-transfer solution using CFD.
• Assessment of temperature stratification and local air movement.
• Identification of potential draught-sensitive and thermally non-uniform regions.
• Post-processing of temperature, velocity and airflow patterns at representative occupant levels.
• Engineering interpretation and preparation of a complete CFD report.

CFD Model Development

1. Geometry Preparation

The first stage was to convert the architectural and MEP information into a CFD-ready representation. Excessive geometric detail can increase mesh size without improving the prediction of the occupied-zone environment, while excessive simplification can remove flow restrictions that materially affect the result.

SuperDesignTech therefore applied engineering judgement to preserve the features relevant to airflow and heat transfer, including occupied volumes, partitions, major obstructions, supply terminals, return paths and significant thermal loads.

2. Mesh Strategy

Mesh generation was treated as an engineering quality-control activity rather than a purely automated operation. Local refinement was considered around supply-air regions, return-air openings, major obstructions and areas where strong velocity or temperature gradients were expected.

The objective was to obtain adequate spatial resolution in the occupied zone while keeping computational cost under control. Mesh quality checks and solution sensitivity were used to reduce the risk that numerical discretisation would be mistaken for a physical building effect.

3. Physical Models and Boundary Conditions

The CFD setup was developed around the dominant physics of the building environment: turbulent airflow, convective heat transfer and buoyancy-driven flow. Depending on the operating case, the model incorporated the thermal influence of internal loads and building-envelope conditions.

Supply-air boundary conditions were defined from the available HVAC design information. Return-air openings were represented to reproduce the intended air-extraction mechanism. Internal surfaces and heat-generating components were assigned thermal conditions consistent with the engineering information available for the project.

Thermal Comfort Evaluation

A technically useful Thermal Comfort Analysis must go beyond a single average temperature. SuperDesignTech evaluated the CFD results spatially to understand the occupant experience. Typical engineering outputs included:

PMV and PPD in a CFD-Based Workflow

Where project inputs permit, Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) can be used to interpret thermal comfort. These indices require more than air temperature: metabolic rate, clothing insulation, air speed, humidity and mean radiant temperature are important inputs.

For CFD-based assessment, the engineering challenge is to avoid treating PMV as a single room-wide number when the environmental conditions vary significantly from one location to another. Spatial CFD results can instead be evaluated across representative occupant locations or planes, allowing the engineering team to identify non-uniform comfort zones.

This approach is particularly valuable in large open-plan areas, high-occupancy spaces, buildings with extensive glazing, spaces with high equipment heat loads and areas where supply-air jets interact with architectural obstructions.

South Africa Project: Engineering Findings

The South African construction project demonstrated why a building can satisfy a nominal HVAC design intent while still requiring detailed investigation of the occupied-zone environment. The CFD model allowed the project team to visualise the three-dimensional relationship between supply-air distribution, internal heat sources, buoyancy and return-air paths.

The analysis focused on identifying regions where airflow distribution could produce thermal non-uniformity or locally elevated air velocity. The CFD post-processing made it possible to distinguish between global system behaviour and localised effects caused by geometry, equipment or air-terminal placement.

Based on the simulation findings, engineering recommendations were documented for the project team. Depending on the design condition, these recommendations can include adjustment of supply-air direction, terminal positioning, airflow rates, return-air strategy, diffuser selection or local heat-load assumptions. The final recommendation set was developed from the project CFD results rather than from generic HVAC rules.

Quality Control of the CFD Analysis

For a professional CFD study, producing colourful contours is not the definition of success. The credibility of the result depends on the complete modelling chain: geometry, mesh, physical assumptions, boundary conditions, solver settings, convergence behaviour, sensitivity checks and engineering interpretation.

SuperDesignTech's review process included checks of model setup, mesh quality, boundary conditions, convergence behaviour and physical plausibility of the resulting flow field. Results were then converted into an engineering report designed to be understandable to both technical stakeholders and project decision-makers.

Software and Computational Infrastructure

SuperDesignTech is a licensed user of ANSYS Fluent and Cadence DCX. The company also identifies as an early user and pioneer of Rescale Cloud Simulation for cloud-based engineering simulation. These technologies support different classes of engineering workflows, from detailed CFD modelling to large-scale computational environments.

The South African building study was developed as a project-specific CFD workflow. Software selection and solver configuration were determined by the physics, geometry, operating conditions and reporting requirements of the assignment.

SuperDesignTech's CFD Engineering Team

SuperDesignTech operates with six full-time CFD engineers supporting global customers through a continuous engineering delivery model. The team works across international time zones and supports CFD applications involving buildings, HVAC, thermal management, data centres, industrial equipment and other engineering systems.

The company has been providing Thermal Comfort Analysis capabilities since 2009, giving its engineers long-term experience in interpreting airflow, heat transfer and building-environment simulation problems.

Why CFD Analysis Adds Value to Construction Projects

CFD Analysis can be performed before construction or during design development, when modifications are significantly less expensive than physical changes after completion. For building projects, a well-designed CFD study can help answer questions such as:

• Will supply air reach the intended occupied zones?
• Are there regions of excessive air velocity?
• Where can thermal stratification occur?
• Are internal heat loads creating local hot spots?
• Does the return-air arrangement remove air effectively?
• How does a proposed diffuser or HVAC modification change the indoor environment?
• Which design option provides the best balance between comfort and energy-conscious operation?

From CFD Results to Engineering Decisions

The most valuable CFD report is not simply a collection of contour plots. It connects simulation evidence to a design decision. For the South Africa project, SuperDesignTech structured the deliverable around model assumptions, operating cases, results, interpretation, limitations and actionable engineering recommendations.

This distinction is important for construction projects involving multiple stakeholders. Architects, MEP consultants, HVAC contractors, facility teams and client representatives may all need different information from the same simulation. A professionally prepared CFD report translates the underlying numerical solution into information that can be reviewed and acted upon.

Artificial Intelligence and the Future of CFD Services

SuperDesignTech is also leveraging the latest Artificial Intelligence (AI) tools to improve engineering productivity and help reduce cost and delivery time for global customers. AI is being considered as an engineering productivity layer around the CFD workflow rather than as a replacement for engineering judgement.

Potential applications include accelerating repetitive geometry and data preparation, automating portions of simulation post-processing, classifying large result datasets, identifying patterns across simulation cases, improving reporting workflows and helping engineers focus more time on physics, validation and design decisions.

The long-term objective is straightforward: combine experienced CFD engineers, established simulation technology, cloud computing and responsible AI-assisted workflows to deliver technically defensible results faster and at a competitive cost.

Conclusion

The South African construction project is a strong example of how Thermal Comfort Analysis using CFD can provide deeper engineering insight than conventional temperature checks alone. By resolving airflow, heat transfer and spatial temperature behaviour, CFD enables project teams to understand the indoor environment before design decisions become expensive to change.

SuperDesignTech has been working on Thermal Comfort Analysis since 2009 and supports international customers with dedicated CFD engineering resources, ANSYS Fluent, Cadence DCX and cloud simulation capabilities. Its experience spans building airflow, HVAC CFD, data-centre environments and complex engineering applications.

For organisations planning a new construction project, HVAC redesign, building-performance study or indoor-environment investigation, a project-specific CFD Analysis can provide the quantitative evidence needed to make better engineering decisions.

Frequently Asked Questions

What is Thermal Comfort Analysis?

Thermal Comfort Analysis evaluates whether the indoor environmental conditions are likely to provide an acceptable level of comfort for occupants. Depending on the project, it can consider temperature, air velocity, humidity, mean radiant temperature, metabolic activity and clothing insulation.

Why use CFD for Thermal Comfort Analysis?

CFD can resolve the spatial distribution of airflow and temperature, helping engineers identify local effects that may be hidden by a single average room temperature.

What software does SuperDesignTech use for CFD?

SuperDesignTech is a licensed user of ANSYS Fluent and Cadence DCX and has experience with Rescale Cloud Simulation for cloud-based computational workflows.

Can CFD be used before construction?

Yes. CFD can be integrated into design development to investigate HVAC distribution, thermal conditions, airflow paths and alternative design configurations before physical construction changes become costly.

How long has SuperDesignTech provided Thermal Comfort Analysis?

SuperDesignTech has been working on Thermal Comfort Analysis since 2009.