Prefect Controls Irus system helps Curlew Capital cut heating energy consumption by 50%

Building Energy Management System installation saves nearly £70,000 annually

Curlew Capital owns The Refinery, a purpose-built student accommodation development on Bingley Street, Leeds. Opened for the 2021/22 academic year, the eleven storey building provides accommodation for 407 students across studio apartments and cluster flats, with shared amenities including social spaces, a cinema and a gym. The property is managed by Fresh Student Living. 

Within the first two years of operation, Curlew’s asset management team identified unexpectedly high electricity consumption. Heating alone accounted for around 73% of total electricity use, prompting the team to explore solutions that could improve energy efficiency while maintaining resident comfort. 

The Refinery, a purpose-built student accommodation development in Leeds.

The challenge: Reducing excessive heating demand and energy costs in student accommodation 

Several factors contributed to the high heating demand at the Refinery: 

• Residents could override in-room heater programming and sometimes set temperatures as high as 30°C; 
• Windows were frequently opened while heating remained active; 
• Continuous operation increased failure rates of the original panel heaters and raised maintenance costs. 

These behaviours created both financial pressure and a material challenge for the company’s Net Zero pathway. As Kristian Mills, Director of Asset Management at Curlew Capital, said, the team needed a system that could monitor room usage and provide centralised control while maintaining resident comfort.  

The solution: Centralised management with Prefect Controls’ Irus system 

To address the issue, Curlew Capital selected the Irus Building Energy Management System (BeMS) developed by Prefect Controls. The Irus system, listed on the ETL under the HVAC Building Controls category, allows operators to monitor and control heating in individual rooms through a web-based portal.  

According to Kristian Mills, “There were three distinct factors that made us decide to deploy Irus in our buildings: the availability of data on how bedrooms are being used, the lowering of energy costs and the reduction to our carbon footprint”. 

Centralised monitoring and control of heating across the building.

The Irus system manages heating through three distinct operational modes. The Frost/Off mode maintains a minimum temperature to prevent damp and mould when rooms are unoccupied. The Setback mode provides a comfortable background temperature, typically set at 18°C. Finally, the Boost mode allows occupants to temporarily increase room temperature to a predetermined temperature, i.e. 23°C for a chosen time, typically 45 minutes before the system returns to Setback mode. Rather than restricting heating, the system reduces unnecessary energy use when rooms are unoccupied or when windows are opened.  

Installation began in early 2023 and was completed in just under four weeks while the building remained fully occupied. In total, 493 control units and heaters were installed across bedrooms, kitchens and communal areas. The system uses Mains Borne Signalling (MBS) to transmit data through the building’s existing electrical wiring, removing the need for additional data cabling. Each room installation took around 30 minutes, which minimised disruption for residents. 

Irus control unit installed in a student bedroom.

Results: 50% reduction in heating energy consumption and a three-year return on investment 

Operational half-hourly data were analysed by Gareth Chaplin at Prefect Controls. The analysis compared twelve months of pre-installation data with the twelve months after the system was commissioned. 

Decrease in overall consumption as well as heating energy usage.

Key outcomes  

Prefect Controls reported the following results: 

• Heating energy consumption reduced from 598,892 kWh to 301,910 kWh. 
• Total electricity consumption reduced from 816,064 kWh to 575,420 kWh. 
• Heating’s share of electricity reduced from 73% to 52%. 
• Energy use per bedroom reduced from 1,464 kWh to 738 kWh. 
• Estimated annual financial savings: almost £70,000. 
• Expected payback: just over three years. 

Beyond cost savings, the system supplies building managers with detailed data on room conditions, including humidity and occupancy, and flags potential use of unauthorised supplementary heaters. These operational benefits support reporting for ESG and GRESB. 

Kristian Mills said, “To see a 50% reduction in heating load and close to £70K saved in year one is phenomenal. These results highlight just how effective the Irus system has been.” 

A model for energy efficient residential buildings 

The project at The Refinery shows how centralised heating controls can significantly reduce energy use in large residential buildings such as student accommodation. By introducing Prefect Controls’ Irus system, Curlew Capital halved heating energy consumption, reduced total electricity use and achieved substantial cost savings while supporting its longer-term sustainability commitments. Following these results, Curlew Capital is considering adopting the Irus system as a standard specification for future developments. 

More information 

See Prefect Controls’ ETL-listed energy management products for detailed product information. 

To learn more about Prefect Controls, visit their website. 

Find out more about Curlew Capital and its projects on their company website. 

The ETL features a wide range of technologies designed to help businesses reduce energy use and operational costs. Browse HVAC Building Controls and Building Energy Management Systems on the ETL. 

See how other organisations are achieving energy savings with ETL-listed products by exploring more case studies. 

Manufacturers of energy efficient technologies can apply to list their products on the ETL for free. Watch the explainer video and read the manufacturers guide to learn more about the application process.