09 May 2025
At Space Engineering Services, we take pride in developing innovative, energy-efficient solutions tailored to our clients’ needs. Our BIS+ (Booster Integrated Solution) is a testament to our commitment to sustainability, efficiency, and reliability. Designed to integrate refrigeration and heat pump technology into one compact system, BIS+ helps businesses move towards net-zero and decarbonisation goals while optimising operational efficiency.
BIS+ was born from our extensive knowledge of heat recovery in small-format stores and learnings with CO2 (R744) as a refrigerant. Our goal was to scale this up to meet the demands of large supermarkets and distribution centres while maintaining affordability, efficiency, and ease of maintenance.
The key challenges we set out to address included:
BIS+ is a fully integrated refrigeration and heat pump solution designed to operate efficiently throughout the year, adapting to seasonal variations in demand. During the summer months, when evaporator cooling requirements are at their peak, the system operates in full refrigeration mode, ensuring optimal temperature control. However, in winter, the reduced refrigeration demand can result in compressor standstill, leading to wasted energy potential. BIS+ overcomes this by implementing interchangeable operational modes, using 3-way control valves, to keep the compressors engaged and running efficiently all year round. This enables more potential of the pack, improving and enhancing overall energy efficiency.
One key component of BIS+ is its integrated heat exchanger, which captures waste heat generated during the refrigeration process (usually lost to atmosphere) and reclaims it to provide hot water for the mechanical services heating demand. This feature is particularly beneficial in colder months, where heating demand is higher, allowing businesses to maximise energy utilisation while reducing reliance on external heating sources. Additionally, BIS+ leverages a smart control strategy, integrated with Building Management Systems (BMS). This allows for real-time optimisation of energy use, as the controller engages different states or modes to ensure a balance between refrigeration and heating demands.
BIS+ is equipped with additional heat pump compressors, which play a crucial role in maximising energy efficiency across different seasons. During the winter, these compressors operate in heat pump mode, generating on-demand heating while maintaining optimal energy usage. To further improve performance, BIS+ employs a floating suction pressure range (-12°C to 0°C), which automatically adjusts based on ambient conditions, ensuring the ideal balance between efficiency and operation throughout the year.
In the summer, these compressors transition to parallel operation, reclaiming flash gas from the receiver. This process enhances refrigeration efficiency by maintaining stable pressure levels and reducing overall energy consumption. To ensure ideal control, the system incorporates modulating valves and inverters, which enable smooth capacity adjustments based on demand. This innovative concept allows the BIS+ to deliver a highly flexible and energy-efficient solution that meets the dynamic needs of large-scale refrigeration and heating applications.
To further enhance efficiency and system adaptability, BIS+ integrates swing compressor technology, which enables the compressor to modulate between refrigeration and heat pump modes. In the summer, the compressor functions as a refrigeration unit, working alongside medium-temperature suction compressors to meet evaporator cooling demands.
During the winter, the swing compressor transition to heat pump mode, working alongside the heat pump compressors. These utilise a dedicated IT suction line for heating applications. This intelligent switching mechanism minimises compressor downtime, optimises energy usage, and ensures a reliable heating supply even in colder conditions. By reducing standstill time and enhancing potential refrigeration load available. The swing compressor contributes to the overall robustness and efficiency of BIS+, making it a game-changing solution in refrigeration and heat pump integration.
While developing and implementing BIS+, we encountered several technical challenges that provided valuable learning opportunities.
Managing water temperatures and pack modes was a key hurdle, as initial instability led to excessive flash gas generation, requiring adjustments to head pressure and balancing. Optimising efficiency between subcritical and transcritical modes also proved complex, improving the use of the false load evaporators and engaging defrost while maintaining heat and prioritising refrigeration demand. The defrost cycle required fine-tuning due to multiple evaporator circuits, necessitating careful balancing of fan operations to prevent inefficiencies.
Additionally, with no off-the-shelf control solution available, we developed a custom approach by integrating PID loops into the RDM PLC system, smoothing operations and preventing surges. Integrating water controls with M&E contractors was another challenge, requiring close collaboration to ensure optimal system performance.
Furthermore, the plant experienced overload issues during morning start-up, as sudden demand spikes caused high-pressure trips and overloading. To mitigate this, we introduced a minimum night-setting to keep the plant running at a baseline level, ensuring a smoother transition during store openings.
The BIS+ project has successfully transformed refrigeration and heating efficiency, delivering outstanding results across multiple areas. One of the most significant achievements was the replacement of seven traditional HFC-based refrigeration plants with just two state-of-the-art BIS+ packs on R744. This major consolidation not only reduced equipment footprint but also streamlined operations, improving overall system reliability and efficiency.
In addition to refrigeration improvements, BIS+ has eliminated the need for traditional gas boilers. The boilers were replaced with a high-efficiency water pump and tank system. This transition has enabled the system to consistently supply 45°C water temperature, meeting heating demands as managed by the Building Management System (BMS) all year round. The integration of heat recovery process leads to ‘free heating’ during mild periods, such as in spring and autumn, significantly reducing reliance on external energy sources and lowering operational costs.
From an efficiency perspective, BIS+ demonstrates strong performance by delivering high heating output while using less energy compared to traditional split systems. Its overall system design supports significant energy savings, making it a reliable option for more sustainable and cost-effective operation. By successfully validating an integrated heat pump and refrigeration system, BIS+ has set a new benchmark in the industry, proving that a combined approach to heating and refrigeration can deliver both environmental and economic benefits.
The success of BIS+ has also been reflected in high client satisfaction, with businesses seeing tangible benefits in energy efficiency, cost savings, and operational performance. As a result, the project has paved the way for future installations and further collaborations, demonstrating the long-term viability of this cutting-edge refrigeration and heat pump solution.
Building on the success of BIS+, we remain committed to refining and enhancing our approach to deliver even greater efficiency, sustainability, and scalability. A key part of this process involves ongoing collaboration with our clients, working closely with them to fine-tune system design based on real-world performance data and evolving industry needs. By continuously gathering insights from installations, we can further optimise BIS+ to better align with operational demands and sustainability goals.
A major focus area for future development is the refinement of control logic. Our experience with BIS+ has demonstrated the significant impact that intelligent system controls have on efficiency and reliability. We are working on further enhancements to ensure even more precise management of refrigeration and heating demands, reducing energy consumption while maintaining optimal performance. This includes smarter automation, better predictive algorithms, and integration with building management systems (BMS) to maximise energy savings.
Looking ahead, BIS+ is set for wider implementation across additional sites, including an exciting project in 2024 featuring a direct CO₂-to-air heat recovery plant. By supplying the AHU coil with CO2 directly from the pack, this marks a significant step forward in sustainable heating and refrigeration solution, removing the need for water-pumped systems and replacing them with a direct, efficient approach. Eliminating water systems and storage tanks, we aim to simplify installation, reduce maintenance requirements, and enhance overall system efficiency.
Beyond improving heating capabilities, we are also reviewing the opportunity of expanding BIS+ to include cooling functionality alongside heating. This advancement will allow for even greater versatility in temperature management. Additionally, we are exploring the integration of ejector technology, which has the potential to significantly boost efficiency at high pressures by entraining suction refrigerant to reduce compressor work, therefore optimising energy recovery and reducing losses within the system.
Future-proofing BIS+ remains a top priority, as we continue to push the boundaries of innovation in refrigeration and heat pump integration. Our goal is to establish BIS+ as an industry standard for sustainable, high-efficiency solutions, setting new benchmarks for performance and environmental responsibility. With ongoing research, development, and collaboration, we are confident that BIS+ will play a leading role in the future of energy-efficient refrigeration and heating.
As we continue to innovate and refine our solutions, BIS+ stands as a testament to our dedication to creating sustainable, future-ready refrigeration systems. Interested in learning more? Get in touch to see how BIS+ can benefit your operations: www.space-engineering.co.uk/contact-us/.
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