Smarter specs start at the ceiling
Alex McDonald, National RHC & Radiator Manager at Zehnder Group UK, discusses the advantages of radiant ceiling panels for low energy climate control.
Climatisation of large industrial and commercial buildings – including education settings, offices and healthcare facilities – places the highest demands on energy and cost efficient operation, not to mention comfort and wellbeing.
Often freezing cold in the winter and then a sweltering hot box in the summer, the balance of thermal comfort in buildings is a difficult one to achieve. Coupled with rising energy costs to heat and cool, inefficient thermal loss (or gain) is a major factor that has to be avoided.
In parallel, faced with our continued efforts to reach Net Zero goals by 2050 and complex global climate challenges to deal with, economically and ecologically compatible solutions are more important than ever for consideration across the built environment. Energy efficient planning is more critical than ever nowadays for both new-builds and renovations.
Therefore, when specifying a heating and cooling system, low operating costs and high energy efficiency are important decision-making factors. Numerous variables, such as system size, environmental impact and integration with existing infrastructure, significantly influence energy expenses – and therefore demand careful consideration for optimal performance and long-term satisfaction.
A radiant conditioned system ensures efficient and even heat distribution across the whole room space. The heat is provided where it is required – and only there – ensuring that building surfaces are thermally balanced and preventing occupants from feeling too cold or hot due to drafts or uneven temperatures.
Year-round thermal comfort
So, how does this happen? Imagine taking a walk on a sunny winter’s day. Despite it being freezing cold, the sun’s rays warm your face pleasantly. Feels nice, right?
This fundamental natural principle of heat transfer is also achieved through the installation of radiant ceiling panels to heat a building in winter and cool it down in the summer months – achieving year-round thermal comfort with up to 40% more energy efficiency than alternative heating and cooling solutions.
Radiant panels work by directly managing heat exchange between surfaces. Instead of heating the room air directly like a wall-mounted radiator, a radiant ceiling panel utilises the principle of radiant heat: the panels emit the heat energy as infrared radiation, which hits the surfaces and objects in the room and heats them. Similar to the warming effect of direct sunlight, ceiling-mounted radiant panels create pleasant and comfortable temperatures on the ground, even though the ambient air may be colder.
Then in the hotter summer months, the same principle can be reversed and also used for cooling buildings: cold water flows through the panels rather than hot. Since people and objects in the room have a higher temperature, they radiate their heat to the ceiling. Warm air inside the room also rises and gives off its heat to the cooled ceiling. The cooled air flows back down into the room creating a more comfortable temperature.
The systems are especially effective when working in conjunction with reversible heat pumps. The panels stay above dewpoint using a high cooling water temperature of 14 – 18°C for cooling and low heating water temperature for heating of 30 – 45°C. Ideal for achieving highest possible heat pump coefficient of performance (COP) and for minimising asymmetric radiation effects.
The radiant effect saves 2°C air temperature in cooling (>20%), 3°C air temperature in heating (15%), and this radiant efficiency of the radiant system, coupled with the efficiency of a heat pump, makes the solution arguably the most energy efficient heating and cooling system available – even when compared to underfloor heating.
Radiant panels also play an increasingly important role to mitigate the issue of overheating – a growing concern for modern buildings. As summer temperatures continue to rise, the need to meet comfort standards outlined in CIBSE TM52 becomes more critical. The TM52 guidance document not only addresses overheating but also emphasises the importance of maintaining a consistent comfortable thermal environment, considering factors like air temperature, radiant temperature, humidity and air movement.
This is where radiant panels come into their own. They offer a quiet, efficient way to mitigate overheating by circulating cooled water through the system. The cooling ceiling absorbs the heat energy in the room and transfers it to the water-bearing pipe system that runs through the cooling ceiling system. The cool water removes the heat from the surfaces and objects in the room, creating a pleasant coolness and an optimum climate. By influencing the mean radiant temperature (the average temperature of the surrounding surfaces), this improves thermal comfort and reduces the risk of overheating.
Radiant ceiling panels, like Zehnder’s Alumline and the Zehnder ZFP, respond quickly to temperature changes, using up to 40% less energy than traditional air heating methods while providing architectural flexibility.
Design & install
In industrial applications, such as factories and warehouses, radiant panels are typically installed in long strips – up to 50m in length. However, with the growing trend of repurposing industrial spaces for offices, restaurants and residential use, products like the Zehnder ZFP Urban panel have been reengineered into a compact, self-contained unit. This approach simplifies the specification and integration process for heating and cooling systems. There’s also potential to integrate additional features, such as lighting, sensors or speakers, directly into the panel unit, enhancing their versatility.
Installed discreetly on the ceiling, their slim design and ceiling placement saves valuable room space, and they do not pose a burn risk, making them safe for environments with children such as nurseries, schools and universities, as well as healthcare settings for the infirm or elderly. This offers a more practical, energy efficient and adaptable option to ensure a comfortable environment all year round while prioritising space.
These panels integrate seamlessly into all types of lay-in ceilings, especially traditional grid ceilings. They feature a high-quality powder coating finish and a discreet design, ensuring long service life.
Installation is straightforward, as the panels are lightweight and come ready to install with simple hydraulic connections. Unlike earlier industrial radiant panels that required additional headers, connectors and cover plates, the new designs simplify installation by reducing the number of joints and potential leak points, making the process quicker and more efficient.
Radiant ceiling panels make an excellent choice for both commercial and industrial spaces. While smaller models integrate directly into ceilings, becoming almost invisible, recent developments in industrial-style panels now also cater to more design-oriented spaces. These newer panels are suspended in open-ceiling environments, offering both aesthetic appeal and enhanced performance for heating and cooling.
However, in order to achieve the full benefits of radiant ceiling panels, four key considerations need to be thought out in the design and specification process:
• System design: Proper system design and control are crucial for maximising the benefits of radiant panels.
• Dew point: Radiant cooling systems require the system to stay above dew point to prevent condensation forming on panels. Monitoring and controlling this can be done through the BMS control system.
• Integration with other systems: Radiant panels should be integrated with other building systems, such as ventilation and shading, to achieve optimal thermal performance.
• Occupant comfort: The effectiveness of radiant panels in achieving TM52 compliance depends on achieving a balance between comfort and energy efficiency.
As heating and cooling technology continues to evolve, radiant panels are set to become an even more integral part of modern building systems. For consultants and specifiers looking for an adaptable, cost effective, low maintenance heating and cooling solution, radiant panels present a forward-thinking option that aligns with both contemporary design and sustainability goals.
