Thermal Modelling

Energy and thermal comfort Modelling

Stickland Wright have the in-house capabilities and expertise to produce detailed building energy modelling and thermal comfort assessments using IES 3D environmental software. ‘Environmental modelling’ is generally required for one of two main reasons: 1. To assess the energy demands of a building, in particular heating energy demand, and look at options to reducing the energy demand; 2. To carry out dynamic thermal modelling ‘overheating assessments’ to develop designs that are tailored to be at comfortable temperatures year round.

What is Energy Modelling?

During the design development stage it is highly recommended to carry out analysis of the operational energy requirements (heating, hot water, electricity, etc.) of different design options to ensure that energy efficiency is built into the design from an early stage.  A virtual 3D model of the project is created and data relating to insulation, orientation (solar gain), windows and ventilation is programmed in.  This process can be followed for existing buildings, renovations & extensions and new build developments. Once the baseline model is created it is then possible to test options for energy efficiency improvements, for example by altering the geometry of the design, or by increasing the proposed insulation levels.  Results can be clearly presented in graphs to explain the benefits of certain design decisions from an energy efficiency perspective – ultimately we are aiming for the lowest possible operational energy which will ultimately result in lower bills for the lifetime of the building.


What are Overheating Assessments for ‘Part O’?

Part O came into effect as a building regulation requirement in 2022 and essentially aims to ensure that all new-build residential developments will not suffer from overheating in the summer months.  Severe overheating in new buildings has unfortunately become commonplace with increased levels of insulation and airtightness.  It is recommended to carry out the overheating investigation at an early stage in the design process because it might be necessary to alter windows, or even spatial design, to ensure compliance can be achieved.  There are two generally accepted ways to demonstrate compliance with Part O, the ‘simplified’ method and the more detailed ‘dynamic thermal modelling’.

Simplified method

For new build projects with a traditional form and conventional heating & ventilation systems the simplified method can be used to prove that the building will not overheat for an unacceptable amount of days per year.  Stickland Wright have developed a bespoke spreadsheet that follows through the process outlined in the building regulations to ensure that the building achieves the requirements.  Data is input about building orientation, windows, openings and ventilation to calculate the % of overheating that may occur.  Key rooms, such as bedrooms are also looked at in isolation to ensure that there will not be localised overheating in any ‘high risk’ areas.  One factor that is a great help when approaching a new project and aiming to pass with the simplified method is to ensure that effective cross ventilation can be incorporated into the design.

Dynamic method

If the simplified model cannot prove that overheating will not occur and there are no design changes that can be made to mitigate against overheating then the next step would be to assess the design using a more detailed ‘dynamic thermal model’.   Otherwise, dynamic thermal modelling might be the first port of call if the building is more complicated in form or if it will use ‘modern’ ventilation systems such as MVHR.  This method relies on virtual 3D environmental modelling in software such as IES.  All the relevant project parameters are included in the model and then simulations can be run to ‘test’ different scenarios to mitigate overheating.  If a design has not passed using the simplified method it may be possible to show that overheating risk can be reduced by, for example, inclusion of effective mechanical ventilation.

Could I just use air conditioning?

In the first instance Part O emphasises reducing summer solar gains and using ‘passive’ ventilation methods.  Where overheating is still a risk ‘active’ mechanical ventilation and other strategies can be evaluated using the dynamic method to try and demonstrate compliance.  Technologies such as air-conditioning  can only be used as a last resort due to their inherent energy demand.   If it is ultimately necessary to use air-conditioning, for example due to an un-compromising design or restrictions on openable windows, then the additional energy use must be compensated for elsewhere.  Energy efficiency measures such as increased insulation and renewable electricity generation are often required in these cases.    This is covered in a separate part of the building regulations (Part-L) and generally will be accounted for in the SAP calculations that must be undertaken. 

We would always recommend mechanical ventilation and heat recovery (MVHR) systems where any form of mechanical ventilation is required as these have fantastic energy saving potential for the winter months and can be integrated with air-conditioning type systems should this be required in the summer months.  However, wherever possible we will always design with low energy and passive cooling methods in mind and aim for building regulation compliance using the simplified method in the first instance.  Stickland wright believe that simplicity is key to achieving optimum energy efficiency and added value for our clients.  

How can we help?

Stickland Wright in house team can provide design stage Thermal Modelling for your projects. We work with clients to meet their additional targets and comply with the building regulations to provide designs that achieve the energy performance targets for dwellings.

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Other Additional Services

SAP Assessments

SAP (Standard Assessment Procedure) is the methodology used by the government to assess and compare the energy and environmental performance of dwellings. SAP reports are required for all residential new build projects, some types of residential extension, conversion to dwelling and residential retrofit projects. These reports are the methodology behind the production of EPC calculations. Our in-house team can produce SAP and EPC reports for your projects.

Thermal Bridge Modelling

Thermal bridges are thermally weak points in a building’s envelope which allow heat to pass out of the building very quickly. Thermal bridges can account for up to 30% off heat loss in buildings, even where they are perceived to be well insulated. Avoiding bridging is therefore a clear priority.

Passivhaus and Active House Design Consultants

PassivHaus and Active House are internationally recognised as the leading quality standards for low energy building performance.  For projects that aspire to achieve the highest levels of energy efficiency, working to these standards is highly recommended.  Stickland Wright have experience in delivering projects with both!