Construction practice has hardly evolved in 40 years, and nor has productivity. Houses as a product have been criticised as cost-inefficient and failing to meet the market demand. Innovation market failures drove InnovateUK to launch Project Sirius, funded through the Industrial Strategy Challenge Fund –  Transforming Construction theme.

Leading Midlands social housing landlord whg led a consortium on the two-year project exploring the potential of offsite modular housing construction. Collaborating on the project were Birmingham City University, Energy Systems Catapult, Hadley Group, Northmill Associates, and QM Systems.

The platform-based ‘Designed for manufacture and assembly’ (DFMA) house has components manufactured in a factory using advanced manufacturing systems and transported for assembly on-site. As well as addressing local housing shortages, benefits are expected to include reduced energy bills, new business opportunities and reduced construction costs. The objectives of the project were to:

• Enhance the manufacturing process of DfMA houses by adopting a ‘kits-of-parts’ approach to minimise rework, production of waste and risks.
• Develop standardised pods units and panel units to boost automation, precision and quality of the manufacturing process
• Adopt best practices of site assembly, onsite storage and transportation to minimise physical efforts and logistical constraints
• Deliver design solutions that maximise energy efficiencies across the project’s lifecycle at a minimum whole-life cost.

Energy Systems Catapult undertook dynamic modelling assessments of the DfMA houses using our Home Energy Dynamics (HED) tool-kit to calculate the building’s energy and thermal efficiency for various home configurations, building materials, power and heating systems, and occupancy profiles.

Key points

Dynamic simulation using HED was used to identify feasible combinations of improvements to building fabric, heating system and control to meet emissions, comfort and running cost requirements without putting unsustainable stress on the distribution networks.

By taking a whole-home approach, including the energy-related behaviour of occupants, HED allows analysis of the impacts and interactions between all aspects of the home’s energy use.

The work presented in this report evaluates the energy performance, carbon emissions and comfort metrics in Walsall Housing Group prototype modular steel-framed house. Three house configurations and three levels of heating standards and occupancy profiles were explored. The Gold standard included a heat-pump based heating system with solar PV and battery storage; Silver standard includes space heating (SH) is provided by electric panels, the domestic hot water demand (DHW) is met by Mixergy hot water cylinder plus solar PV; and the Bronze standard has electric panels for SH and DHW was met by Mixergy cylinder.

The results of the Energy Modelling of Modular DfMA Housing for Walsall Housing Group study were that:

• Significant energy efficiency gains and emissions reductions can be achieved using this innovative housing design;
• The high peak electricity demand in the houses with electric panels, meant if a large number of houses on the same network adopt electric heating, grid reinforcement might be required;
• Integrating solar PV and battery storage system could contribute to lowering the peak electricity demand;
• Employing a heat pump coupled with solar PV and battery storage system delivered the greatest benefits.

The results will feed into Birmingham City University’s knowledge-based engineering (KBE) tool which can be used to select optimal building configurations, materials, and energy management strategies to maximise efficiency and minimise costs.