This article delves into the principles of thermal modelling, its key benefits, and its integration with other sustainability tools.
We will explore how thermal modelling can help optimise building design, enhance energy efficiency, and ensure occupant comfort, ultimately contributing to a more sustainable built environment.
Table of Contents
Why Thermal Modelling Matters
In Australia, where energy consumption and greenhouse gas emissions from buildings are significant concerns, incorporating thermal modelling into the design process has become increasingly important.
The Australian Government’s National Construction Code (NCC) and the Building Sustainability Index (BASIX) set stringent energy efficiency standards.
By utilising thermal modelling, developers can ensure compliance with these regulations while creating sustainable and financially viable buildings.
Source: Australian Building Codes Board
By simulating the heat flow and energy performance of buildings, thermal modelling allows architects and engineers to make informed decisions that can:
- Significantly reduce energy consumption
- Improve occupant comfort
- Enhance overall building sustainability
Australia’s net energy use increased by 2% in the 2022–23 financial year to 23,294 petajoules [source], underscoring the need for effective energy efficiency strategies in building design and operation.
Thermal modelling plays a crucial role in mitigating this rising demand by enabling smarter, more efficient buildings that consume less energy while maintaining optimal performance.
What is Thermal Modelling?
Thermal modelling is a digital simulation process used to analyse the energy performance of buildings.
It assesses how heat flows through a building, considering factors such as:
- Insulation
- Ventilation
- Solar gain
- Internal loads
This modelling enables designers to predict temperature fluctuations, energy consumption, and overall thermal comfort under various environmental conditions.
When is Thermal Modelling Required?
Thermal modelling is a requirement in several key scenarios, including:
- Compliance with Building Codes: Meeting energy efficiency requirements under the NCC, BASIX, or JV3 performance assessments.
- Sustainability Certifications: Supporting ratings such as NatHERS (Nationwide House Energy Rating Scheme) and Green Star certification.
- Building Optimisation: Enhancing energy efficiency and thermal comfort in both residential and commercial developments.
- Retrofitting and Renovations: Evaluating energy performance improvements for existing buildings.
- Specialty Projects: Projects with specific environmental conditions, such as passive house designs or net-zero energy buildings.
How Thermal Modelling Works
Thermal modelling involves the use of specialised software to create a virtual representation of a building.
This virtual model incorporates various factors such as:
- Building orientation (solar gain)
- Materials
- Insulation
- Window systems
- HVAC systems
The thermal modelling software then simulates the heat flow through the building envelope and HVAC systems under different climatic conditions.
The Process of Thermal Modelling
- Data Collection: Gathering details on the building’s design, materials, orientation, and environmental conditions.
- Software Input: Entering data into specialised thermal modelling software such as IES-VE, DesignBuilder, or EnergyPlus.
- Simulation & Analysis: Running simulations to assess energy performance, heat gain/loss, and occupant comfort.
- Optimisation: Adjusting design elements to improve energy efficiency and thermal comfort.
- Reporting & Compliance: Generating reports to demonstrate compliance with NCC, BASIX, JV3, and other regulatory requirements.
This analysis helps to predict energy demand and consumption, indoor temperature, and humidity levels throughout the year.
It also considers factors such as solar radiation, ventilation and shading, providing comprehensive insights into building performance.
How Does Thermal Modelling Measure Performance?
Thermal modelling measures building performance using various metrics, including:
Energy Consumption:
Evaluating heating and cooling energy requirements to understand a building’s operational efficiency.
By analysing energy use over time, thermal modelling helps optimise insulation, HVAC design, and passive solar strategies to reduce energy demand.
Thermal Comfort Indices:
Using measures such as the Predicted Mean Vote (PMV) and Operative Temperature, thermal modelling ensures that internal temperatures remain within a comfortable range for occupants throughout different seasons.
This is critical for maintaining a balanced indoor climate that reduces reliance on artificial heating and cooling.
Solar Heat Gain Coefficient (SHGC):
Assessing the effectiveness of glazing systems in managing solar radiation.
High SHGC values indicate greater solar heat gain, which can be beneficial in colder climates but problematic in warmer ones.
Modelling helps determine the right balance to optimise thermal performance.
Ventilation Efficiency:
Determining airflow and natural ventilation effectiveness by simulating how fresh air circulates through the building.
Proper ventilation can improve indoor air quality and reduce cooling loads, particularly in passive design strategies.
Carbon Footprint Analysis:
Estimating the environmental impact of a building’s energy use by quantifying greenhouse gas emissions associated with heating, cooling, and electricity consumption.
This helps in developing sustainable designs that align with carbon reduction goals.
Key Benefits for Building Design
Energy Efficiency
Thermal modelling enables designers to reduce operational energy costs by optimising building envelope design, HVAC systems and renewable energy integration.
By minimising energy consumption, buildings can significantly decrease their carbon footprint.
Thermal modelling helps identify energy-saving opportunities, such as strategic window placement and insulation levels and optimisation.
Occupant Comfort
Thermal modelling enhances thermal comfort throughout the year by ensuring consistent internal temperatures.
Thermal comfort refers to the state of mind that expresses satisfaction with the thermal environment.
Factors influencing thermal comfort include:
- Air temperature
- Humidity
- Air movement
- Radiant temperature
By simulating thermal performance, designers can create buildings that maintain optimal indoor conditions.
Regulatory Compliance
Thermal modelling can help building designers comply with energy efficiency standards and building regulations, such as the National Construction Code (NCC) in Australia.
By demonstrating compliance through accurate simulations, designers can avoid costly retrofits and ensure that their projects meet the required standards.
It’s important to note that, as per JV3 assessments, buildings must also meet specific thermal comfort targets.
This means that the insulation, glazing, and HVAC systems must be designed to maintain comfortable indoor temperatures, often measured using the Predicted Mean Vote (PMV) index.
Design Optimisation
Thermal modelling allows designers to experiment with different design options and identify the most energy-efficient and comfortable solutions.
By analysing the impact of various design choices, designers can refine their designs to achieve optimal performance.
NatHERS and JV3: The Role of Thermal Modelling
Both the Nationwide House Energy Rating Scheme (NatHERS) and JV3 energy assessments rely on thermal modelling to evaluate a building’s energy performance.
- NatHERS: Focuses on residential buildings and uses a star rating system to indicate a home’s energy efficiency.
- JV3 Assessments: Used for commercial buildings, allowing for trade-offs between building elements to achieve overall compliance.
Thermal modelling is essential in both methods to simulate a building’s response to its environment, providing accurate data on heating, cooling loads, and energy performance.
This approach ensures compliance while enabling cost-effective and sustainable design decisions.
What Does Thermal Modelling Cost?
The cost of thermal modelling varies depending on several factors, including:
Building Size and Complexity: Larger or more intricate projects require more detailed simulations.
Software and Tools Used: Advanced modelling software may influence costs.
Regulatory Requirements: Compliance with specific standards like JV3 or NatHERS may impact the level of analysis required.
Consultant Expertise: The experience and credentials of the energy consultant conducting the modelling.
Generally, costs for residential thermal modelling assessments start from $180, while commercial projects requiring JV3 assessments start from $500, depending on project scope.
Integration with Other Sustainability Modelling Tools
Thermal modelling synergises with daylight and energy modelling to provide comprehensive insights into building sustainability.
Advanced parametric modelling enables the integration of multiple sustainability metrics, facilitating holistic building design.
The future of ESD consulting lies in leveraging advanced modelling techniques to drive sustainable design.
Parametric modelling enables designers to explore complex relationships between building components and environmental factors. This integrated approach fosters sustainable, efficient and occupant-centric buildings.
Leverage the Power of Thermal Modelling
Thermal modelling is a critical tool for sustainable building design.
By understanding the energy usage and thermal comfort of buildings at the design stage, architects and engineers can make informed decisions that reduce energy consumption, improve occupant comfort, and minimise environmental impact.
As ESD consultants, we can help you leverage the power of thermal modelling to create sustainable and resilient buildings that meet the stringent requirements of JV3 or NatHERS assessments.
For more detailed information on thermal comfort and JV3 requirements, please refer to our article or contact us on 1300 864 944.
Albert Burton is the founder of Green Choice Consulting, leading a national team that delivers fast, accurate ESD reports for residential and commercial projects. With expertise in sustainability and business, he leverages advanced technology to streamline compliance and reduce costs for clients.
