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Modelling new housing developments

Carmarthenshire new build

Carmarthenshire County Council invite the LBCE to advise on the planning and designing of 46 new homes across two sites within the county.

We will also undertake computer modelling to enhance the designs and incorporate low carbon technologies to reduce carbon emissions. As part of the Council’s Affordable Housing Delivery Plan, these 46 new homes will be added to the Council’s existing social housing stock and rented to people on their ‘Housing Choice Register’.

The Council shared their housing designs with the LCBE team who created computer models to explore the potential low carbon solutions that would reduce heat loss and enable on-site energy generation using renewable power, as well as reduce energy costs for future residents whilst reducing carbon emissions.


The objectives were to:

  • optimise the design of the 46 homes to achieve low energy costs and maintain internal comfort
  • integrate renewable energy generation and storage technologies, where appropriate, to reduce energy costs for future residents
  • show the benefits of replicable low carbon solutions on domestic new build housing using modelling

Low carbon solutions included:

  • reduce energy demand by using construction materials which minimise heat loss and that have a high performance and reliability
  • install low energy lighting throughout
  • install air source heat pumps (ASHP) combined with mechanical ventilation with heat recovery (MVHR) systems
  • investigate the potential to generate energy using solar photovoltaic (PV) panels and store energy on-site


The computer modelling enabled the team to make the following recommendations:

  • improving the construction materials with higher performance insulation within wall and floor would reduce heat loss from the home
  • triple glazed windows would reduce heat loss from the home but would add significant cost
  • LED lighting would reduce energy costs and the related carbon emissions
  • installing air-source heat pumps with mechanical ventilation and heat recovery systems would provide the houses with heating, hot water, and ventilation through one system
  • solar PV panels could be applied to each of the houses to generate energy on-site and reduce carbon emissions
  • only some houses would generate enough energy to benefit from having a battery storage system installed due to the differing orientations of the houses on site

If all of the above options were incorporated into the design of the new houses, negative annual CO² emissions could be achieved.

As a result of these recommendations, the Council have gone beyond the current Building Regulation standards and incorporated higher levels of thermal insulation, solar PV panels, energy efficient gas heating and LED lighting into all of the new houses at these two sites. Also, two of the four-bedroom houses will adopt more of the recommendations to test the latest technologies.

Lessons learnt

Although the designs of the homes are similar, their potential to gain heat from the sun through the windows and generate energy from solar PV panels is very different. This is a particularly important consideration when selecting the most suitable technologies for each property.

Detailed modelling showed which roof spaces would generate the most energy and the potential amount of energy generation for each property. Based on orientation, some houses could have panels on both roof pitches to generate energy whilst others would only benefit from solar PV panels on one side of the roof.

The modelling enabled the team to identify which houses had the potential to generate a lot of energy from the solar PV panels and could benefit from having a battery system installed to store this energy. Not all houses would benefit from having a battery system installed as the generation capacity of the solar PV panels is not enough.

It was important that the computer modelling reflected scenarios for houses that would not gain much heat from the sun and those that would, as their heating and cooling demands would be quite different.

The project showed the benefits of using computer modelling to inform building design and supported the application of the whole energy system-based approach in housing.

The project provided the Council with credible evidence of the whole house systems approach which has enabled them to adopt and test innovative technologies, which will influence their future Policy aims.

Project team

The project team includes:

  • LCBE team at the Welsh School of Architecture, Cardiff University
  • Carmarthenshire County Council.