Making the right choice
Indoor air quality has a massive impact on the health and comfort of a building’s occupants, and if not appropriately managed it can considerably reduce worker concentration levels and directly contribute to staff sick days. It is therefore essential, when considering options for heating, that the appropriate system is selected. Such a system needs to provide adequate heat for the occupants whilst ensuring that the movement of pollutants within the room is kept to a minimum.
With this in mind, one solution that should be a top consideration for consultants working on projects such as hospitals, sports halls, offices, reception areas, warehouses and factories, is radiant heating.
Radiant heating emulates the natural solar heating process. Just like the sun’s rays, radiant heaters transfer heat to people and solid surfaces in a room, directly warming objects, rather than the air. Minimal losses occur on the way from ceiling to floor, and temperature distribution is very even. Radiant heating acts in much the same way as lighting, in terms of dispersion and reflection.
By contrast, fan assisted systems heat the air, which inevitably rises, so that the air temperature is significantly higher near the ceiling. The difference is more significant the higher the temperature of the air produced by the heater and the higher and less insulated the building.
With radiant heating, the problem is greatly reduced and can be almost eliminated entirely. The European standard EN 12831 (method for calculating heat losses from a building), appendix B1, envisages for buildings up to 10m in height a total heat loss increase coefficient of just one if the heating system used is prevalently radiant, or a value greater than one if the system is primarily convective.
Further, the human body is sensitive to both the temperature of the air and the temperature of the surrounding walls and windows. For this reason, a typical problem area in many applications is heat loss through large glazed areas, where cold radiation is created by the glass surface. Radiant heaters can reverse this process by warming the cold surface and allowing comfortable conditions close to glazed areas.
In rooms heated by radiant panels, the temperature of the walls and floor are higher than in rooms heated by direct air heating systems, giving occupants benefit from a more comfortable, natural feel in the air quality, with significantly lower air temperatures. In well insulated rooms, radiant heating can give the same levels as air-heating systems at a temperature that is 3°C lower. This brings considerable energy savings for the building owner – for every 1°C reduction in air temperature, an energy saving of about 5% is achieved.
This is confirmed in appendix B2 of EN 12831. In the case of rooms heated with radiant systems EN 12831 envisages the calculation of building heat losses due to the infiltration of outside air, using not the operating temperature (arithmetic mean between the air temperature and the mean radiant temperature) but the air temperature alone. A lower air temperature, therefore, means less heat loss from the building due to the infiltration of outside air.
Air quality aside, a third energy benefit is apparent, as heating by radiant panels does not require the use and consumption of electrical energy to supply the fans that are necessary for other hot air heating systems. The heat loss of buildings heated with radiant panels is much lower than it would be if the same building used direct air heating systems. A lower heat loss means less energy consumption for the same conditions of comfort.
As radiant heaters keep air movement to a minimum, the spread of dust, bacteria and odours is considerably reduced, offering a clean air solution especially suited to hospitals where the spread of pollutants is unacceptable. They also offer excellent protection against draughts from windows and doors.
Radiant heating also allows spot heating – for example, in warehouses and factories, where it is not viable to heat the whole space. Similarly, they are effective as zone heaters, creating different temperatures in spaces such as small offices, kiosks or individual workstations, resulting in less unnecessary heating of larger spaces. Radiant heaters also provide virtually instantaneous heat, so can be run only when needed.
It is clear that – in accordance with current environmental, air quality and safety concerns – radiant heat provides an optimum heating solution.
As a bonus, radiant heaters perform quietly, are maintenance-free, and take up little space.
The design and installation are also critical factors when selecting a heating system. Frico has paid attention to allowing easy installation and optimal application of radiant heating systems, ensuring a sensible solution for designers. Amongst Frico’s extensive range, the recently launched Comfort Panel SZR, used for water supplied heating/cooling systems, is primarily intended for mounting in false ceilings, but can also be suspended from the ceiling. It has been developed to offer a flat satin-finish surface, discreet countersinks, minimum maintenance and easy and flexible installation. The SZR range is perfectly suited to offices, shops and any other fine spaces.
The Comfort Panel SZR is available in a choice of lengths to fit a standard ceiling grid offering a wide range of outputs, but, still ensures the room temperature can be reduced with maintained comfort thanks to the radiation principle. The SZR, which meets the latest EN standard, has an innovative, all-welded flat pipe construction for better heat transfer and silent operation.
The smoking ban
Last year’s smoking ban has highlighted another issue when considering indoor air quality at premises such as restaurants, pubs, clubs, shopping centres, and any other places where people are using outside areas near open doorways for smoking. This is where an air curtain can help.
The main uses of air curtains are threefold. First, they increase the energy efficient operation of a building by preventing or reducing the unwanted exchange of hot and cold air at an entrance. Secondly, they improve comfort conditions in the entrance area by preventing or warming any incoming cold draughts, creating a pleasant and welcoming environment that is comfortable for staff and visitors alike. Finally, air curtain technology can be used to separate atmospheric zones – for example, between the internal smoke-free environment and the external smoking zones, keeping out air that has been polluted by smoke, traffic fumes, smells, dust or pollen and repelling insects.
Air curtains can be applied to almost any entrance, from smaller retail outlets to larger openings in commercial and industrial buildings. They can be employed as purely functional units, to create an energy efficient air barrier across an opening, or to increase comfort by warming the entrance area for occupants and visitors. They can also contribute to the aesthetic environment, such as a corporate reception area, to keep within the parameters of the architect’s vision. Some of today’s most attractive designs are symmetrical and have stainless steel finishes that hide high quality components and aerodynamically efficient internal geometry, resulting in air curtains that are unobtrusive as well as effective.