The route to lower-carbon HVAC is becoming more complex. Consultant engineers must look beyond the headline carbon credentials of individual technologies and consider how different design decisions affect the building as a whole.
Reducing reliance on fossil fuels remains important, as does the move towards refrigerants with lower global warming potential (GWP). But these decisions must be considered alongside operational energy, whole-life carbon and the practical requirements of the building and its occupants.
This changes the conversation around HVAC innovation. A lower-GWP refrigerant is important, but so is the amount of refrigerant a system requires. Electrifying heating is a significant step, but the efficiency and operating characteristics of the system will influence its whole life carbon impact. As a result, new HVAC technology must support increasingly ambitious environmental targets, while working within the constraints that consultant engineers deal with every day.
The next stage of HVAC decarbonisation therefore requires us to look at carbon reduction from several angles. Two technologies that Mitsubishi Electric will be showcasing at ElementalLONDON this November demonstrate how that thinking is influencing product development.
Give designers better HVAC options as they work towards demanding carbon objectives
Darren Coomber Consultant Account Manager
Taking VRF performance further
VRF is a well-established technology that consultant engineers have worked with regularly. The challenge for manufacturers is how to retain the flexibility that has made VRF so widely used while improving its environmental performance.
Mitsubishi Electric's new City Multi YXM R32 system has been developed with that objective in mind. Compared with the current YNW chassis, the new 30kW YXM achieves an approximate 20% improvement in cooling seasonal efficiency and around a 30% improvement in SCOP. Mitsubishi Electric's modelling also indicates around a 20% reduction in running costs and operational carbon for the 30kW example.
Those efficiency improvements matter because operational energy remains a significant part of the whole-life carbon picture. However, refrigerant choice and system design also contribute to the calculation. YXM uses lower-GWP R32 and Mitsubishi Electric has focused on reducing refrigerant requirements, helping designers address refrigerant-related embodied carbon alongside operational emissions.
Importantly, this development does not mean moving away from the familiar characteristics that have made VRF useful to designers. YXM builds on an established system approach while adding greater flexibility around installation. A smaller outdoor-unit footprint helps where roof space is limited, while compact branch controller boxes are designed for constrained ceiling spaces. The system also offers a 113m vertical extension between outdoor and indoor units, together with five-step low-noise operation and external static pressure options for applications where acoustics or plant location influence the design.
This is an important aspect of practical decarbonisation. Improvements in carbon performance have far greater value when they can be incorporated into workable building designs without introducing unnecessary complexity elsewhere.
Extending the possibilities for heat pumps
The same principles apply to the electrification of heat. Heat pumps are central to the transition away from fossil-fuel heating, but buildings do not all present the same design conditions. Required water temperatures, external ambient conditions and heating loads all influence the viability of a heat-pump solution.
The new Mitsubishi Electric Ecodan CAHV-Z air source heat pump extends the range of options available to designers. Using natural refrigerant R290, with a GWP of 0.02, it can deliver outlet water temperatures of up to 75°C at an ambient temperature of -15°C. Across its 24°C to 75°C flow-temperature range, it can operate without electric boost heaters.
For consultants, that combination provides higher-temperature capability that widens the design territory in which heat-pump technology can be considered. Robust cold-weather performance addresses an obvious requirement for systems expected to provide dependable heating through winter conditions.
CAHV-Z has also been designed with scalability in mind. Up to seven units can be connected in cascade, giving designers greater freedom to match capacity to the application. Anti-simultaneous defrost control prevents all units entering defrost at the same time, helping to maintain heating delivery during cold conditions. Built-in leak detection and an explosion-proof relay are among the measures incorporated to support the safe use of R290.
Turning carbon ambition into engineering solutions
YXM and CAHV-Z address different parts of the HVAC system, but there is a common thread running through their development.
The next stage of decarbonisation will depend on continuous improvement of technologies already available to building designers. That means reducing refrigerant impact and operational energy while widening the range of applications where electrified HVAC can provide a practical solution.
Designers and manufacturers alike must recognise that carbon performance cannot be separated from the realities of building design. Space, acoustics, heating temperatures, system configuration and long-term operation remain part of the consultant engineer's decision-making process.
This is where HVAC innovation has an important role to play. The goal is to give designers better options as they work towards increasingly demanding carbon objectives, without losing sight of how buildings actually need to perform.
Visitors to ElementalLONDON this November will be able to see Mitsubishi Electric's YXM City Multi system and new CAHV-Z air source heat pump and talk to our team about the engineering behind both technologies.
Come and see us at ElementalLONDON from 25-26 November to explore what the next stage of HVAC decarbonisation could mean for your projects. Booth B220.
Darren Coomber is Consultant Account Manager
