Transitioning to LTHW System
Positioning for a Low-Carbon Future
Customised Solutions for Complex Challenges
Background
The hospital is a large healthcare facility built in 1967. Spanning 16,000 m² across multiple blocks, the hospital relies on a steam-based heat network operating at 170°C. This system supplies Low Temperature Hot Water (LTHW) via substations to a variety of emitters, including Air Handling Units (AHUs), radiators, and radiant panels.
Challenge
The aging infrastructure presents significant operational inefficiencies, safety risks, and barriers to adopting low-carbon energy solutions. This includes:
- High Heat Losses: 17% of the energy leaving the plantroom are lost in the primary system and substations due to inefficient steam infrastructure and uninsulated pipework.
- Safety and Reliability Concerns: Steam systems pose higher safety risks due to pressurised gases and their nearing end-of-life pipework, with components like shell-and-tube heat exchangers performing poorly.
- Operational Constraints: The hospital requires minimal disruption to ongoing activities, while limited access to certain areas and asbestos on pipework and in plantrooms complicating the replacement process.
- Transitioning to Low Carbon: Existing high operating temperatures and infrastructure are incompatible with low-carbon solutions, such as connecting to a city-wide heat network or Air Source Heat Pumps (ASHPs).
- Design and Logistical Issues: Underground steam pipe ducts offer limited space for new installations, and one substation's small access door requires careful equipment measurement to ensure feasibility.
FairHeat was engaged to conduct an optimisation study, aiming to suggest improvement to the system’s efficiency, reduction in carbon emissions, and recommendations for future low-carbon energy integration.
FairHeat Solution
FairHeat carried out an Optimisation Study to address these issues, recommending a transition to a more efficient LTHW system. Key solutions proposed included:
System Transition: Replacing the steam system with an LTHW system, reducing the operating temperature to a flow temperature of 65°C.
Equipment Upgrades:
- Replacing inefficient shell-and-tube heat exchangers with plate heat exchangers.
- Installing variable-speed pumps to match flow rates with demand.
- Removing bypasses, diverting three-port valves, and low loss headers to optimise hydraulic performance.
Infrastructure Improvements: Insulating substation pipework to minimise heat losses and introducing water quality equipment to reduce the risk of leaks and equipment damage.
Future Readiness: Evaluating funding opportunities, including Heat Network Efficiency Scheme (HNES) and Public Sector Decarbonisation Scheme (PSDS), to financially support the transition to low-carbon heat sources.
Strategic Implementation: Developing work packages to ensure a phased and minimally-disruptive installation.
Results
If implemented, the proposed optimisations are expected to achieve:
Energy Savings:
- 64% reduction in heat losses.
- 32% reduction in gas consumption.
- 61% reduction in electricity use.
Environmental Impact:
A 33% reduction in CO₂ emissions, with potential for further reductions upon adopting low-carbon energy sources.
Improved Service:
Replacing end-of-life equipment ensured a more reliable and efficient heat supply for hospital operations.
Cost of Works:
Estimated at £8 million, the upgrades are critical for sustainability and durability. External funding opportunities are available to support the low carbon transition such as PSDS which could cover up to 88% of the capital costs.
The recommendations, if implemented, not only address immediate inefficiencies but also set the stage for a low-carbon future, ensuring sustainability and cost-effectiveness for critical healthcare infrastructure.
Highlights
The shift from a high-temperature steam system to an LTHW system operating at a flow temperature of 65°C can significantly improve energy efficiency. This change could reduce heat losses by 64% and gas consumption by 32%, while preparing the hospital for future low-carbon energy integration. Other healthcare facilities with aging steam systems can achieve similar benefits by transitioning to LTHW.
FairHeat addressed specific challenges such as asbestos, limited access, and operational constraints with tailored solutions:
- Phased implementation to minimise disruption to hospital operations.
- Equipment selection accounted for access limitations, ensuring feasibility in constrained spaces.
- Insulation improvements and water quality systems enhanced long-term reliability and performance.
These strategies demonstrate how healthcare developments can optimise their systems without compromising patient care or safety.
FairHeat’s proposed work positions the hospital to prepare the infrastructure for integration with district heating or ASHPs. Furthermore, by leveraging funding opportunities like the Heat Network Efficiency Scheme (HNES) and Public Sector Decarbonisation Scheme (PSDS), this approach ensures compliance with evolving sustainability goals and reduces long-term operational costs.
