RRPPS

 

Project Overview

The Radiation Physics and Protection Service (RRPPS) at Kings Norton, part of University Hospitals Birmingham NHS Foundation Trust, required an upgrade to its Building Management System (BMS). The primary objectives were to improve energy efficiency, enhance air quality control, strengthen gas safety monitoring, and ensure continued compliance with relevant health, safety, and environmental standards.

Working within a defined budget that did not allow for a full system replacement, we extended the existing BMS controls and enhanced the software strategy to deliver more intelligent, responsive, and compliant control. This approach allowed for meaningful improvements without the need for major capital investment.

 

Balanced Ventilation: Comfort Without Compromise

The revised control strategy was designed to achieve a well balanced ventilation system that delivers healthy indoor air quality without compromising occupant comfort or energy efficiency. By modulating airflow based on real time CO2 levels and temperature demand, the system ensures that fresh air is supplied when needed supporting cognitive function, wellbeing, and regulatory compliance, while avoiding unnecessary energy use during low demand periods.

This approach aligns with best practice guidance from the Health and Safety Executive (HSE) and Building Regulations Part F, which recommend maintaining CO2 levels below 800 ppm and supplying fresh air at rates of 5 - 10 litres per second per person. The result is a ventilation system that supports both sustainability goals and occupant health, without sacrificing performance or comfort.

 

Ventilation Control Strategy

A central component of the upgrade involved implementing a dynamic ventilation control strategy based on environmental demand. Duct mounted CO2 sensors were installed to monitor indoor air quality. The sensor readings were compared against a setpoint of 800 ppm to generate a CO2 demand signal. When levels exceeded the setpoint, the system increased ventilation to improve air quality; when levels were below the threshold, ventilation demand was reduced accordingly.

In addition to air quality, space temperature was used to determine heating and cooling demands. The average space temperature was compared to a heating setpoint of 21DegC and a cooling setpoint of 24DegC to calculate respective demand signals. These three demand signals - CO2, heating, and cooling were evaluated, and the maximum value was used to calculate the required ventilation speed.

To ensure energy efficiency and regulatory alignment with NHS sustainability goals, the system was configured with an adjustable minimum fan speed, defaulting to 35%. This represented a significant improvement over the previous setup where ventilation fans ran at a constant 100%. Ventilation speed was modulated using existing Variable Speed Drives (VSDs), which were retained as part of the upgrade.

 

Boiler Room Gas Safety Enhancements

Gas safety in the boiler room was significantly enhanced through the installation of two new sensors: a Carbon Monoxide sensor and a Natural Gas sensor. These sensors were integrated into the BMS and configured to interrupt the power supply to the gas solenoid valve if gas concentrations exceeded safe thresholds. This automatic shut-off mechanism provides a critical layer of protection against potential gas leaks or unsafe operating conditions. The system now complies with gas safety regulations, including IGEM/UP/2, BS EN 15001, and supports NHS requirements for boiler room safety.

 

System Architecture And Strategy

The existing BMS controls were extended and the software strategy was rewritten to incorporate new control logic for ventilation and gas safety. The CO2 sensors and gas sensors were integrated into the system to provide real time data for decision making. The VSDs were used to modulate fan speeds based on calculated demand, ensuring that ventilation was both responsive and energy efficient.

The revised control strategy aligns with best practices in BMS design and supports compliance with NHS HTM (Health Technical Memoranda) guidance, particularly HTM 03-01 for ventilation systems.

 

Outcomes And Benefits

The extension of the BMS at RRPPS Kings Norton delivered a wide range of operational, environmental, mechanical, and compliance-related benefits:

• Fresh air supply is intelligently matched to demand, maintaining healthy CO2 levels and thermal comfort without excessive energy use.
• Reduced ventilation speeds during periods of low demand cut unnecessary power consumption and lowered operational costs.
• Real-time CO2 monitoring and demand-based ventilation control created a healthier indoor environment and supported compliance with HSE and NHS air quality standard
• Mechanical Longevity:

1. Filters experienced less airflow strain, reducing particulate loading.
2. Fan belts operated under lower stress, extending service life.
3. Coils required less frequent cleaning due to reduced dust accumulation.
4. Fan motors saw decreased bearing wear, improving reliability.
5. VSDs operated under less frequent high-load conditions, extending lifespan.

• Real-time monitoring and automatic shut-off functionality ensured compliance with gas safety regulations and NHS Estates protocols.
• The project delivered significant improvements without requiring a full system replacement, aligning with the client’s budget and operational priorities.

 

This project demonstrates that with targeted enhancements and intelligent control strategies, existing BMS infrastructure can be effectively modernized to meet contemporary standards of efficiency, safety, and regulatory compliance while maintaining a healthy and comfortable environment for building occupants.