iklima: Thermal comfort & Well-being Heating and Cooling combined into one system

Transcription

1 iklima: Thermal comfort & Well-being Heating and Cooling combined into one system iklima is the new radiant floor heating and cooling system designed by Georg Fischer. It is the result of over 20 years experience in plumbing and heating field where Georg Fischer keeps a leading position with its high quality products such as multilayer pipes and brass fittings. Thanks to this background, Georg Fischer has developed a state of the art heating and cooling system providing comfort, ease of installation, flexibility, reliability, cost-effectiveness and high performance level. Accurate project design, professional system installation and skilled support team enhance further the quality of this product. 4

2 Thermal comfort Today, environmental comfort relates to a psychophysical state of well being and satisfaction. A comfortable environment is defined conventionally in terms of thermal comfort, lighting comfort, acoustic comfort and air quality. In particular, thermal comfort occurs when there is a thermal equilibrium between human body and its environment, that is when there is no heat transfer and a person feels neither too warm nor too cold. The main factors affecting indoor thermal comfort are: air temperature, mean radiant temperature, air velocity, relative humidity, clothing, body metabolic activity and individual level of fitness. To maintain thermal comfort, the human body must balance the heat generated by the metabolism with the heat lost or gained from the environment. Heat is primarily transferred away from the body by one of the following methods: Convection: heat transfer by contact between a moving fluid and a body in direct contact (through skin) with one another. Convective heat exchange increases with increasing air speed and increased differences between air and skin temperature. Radiation: heat transfer by electromagnetic waves between two objects of different temperatures without contact. Conduction: heat transfer by contact between two object in direct contact with one another to even the temperature difference between them. Evaporation: heat loss through sweating and breathing to cool the body down. UNI EN ISO 7730 standard, Moderate Thermal environments. Determination of PMV and PPD indices and Specification of the condition for thermal comfort, defines the requirements for thermal comfortable environments. According to this standard, thermal comfort conditions are acceptable when ensuring that at least 90% of occupants feel thermally satisfied THERMAL COMFORT >WINTER Variable Operating temperature Vertical air temperature gradient Radiant temperature asimmetry Air velocity Floor temperature Conditions C (RH=50%) max 3 C between 0,1 and 1,1m horizontal direction: max 10 C vertical direction: max 5 C max 0,15 m/s C THERMAL COMFORT - SUMMER Variable Operating temperature Vertical air temperature gradient Air velocity Conditions C (RH=50%) max 3 C between 0,1 and 1,1m max 0,25 m/s 5

3 Thermal comfort - Winter Ideal Heating Curve Ideal heating curve indicates that, for maximum comfort, the warmest temperature is at floor level and cooler temperatures are at head and ceiling levels (even heat distribution). Radiant Floor Heating provides even and comfortable heat distribution. When compared to other types of heating systems, Radiant Floor Heating system most directly approximates the ideal heating curve for the human body, that is warmer at the floor and cooler at head. Radiator Heating Systems deliver heat in a way that is opposed to the optimum heating curve, that is cold feet, hot head. The air is trapped at ceiling level causing an inversion of the ideal heating pattern. 6

4 Thermal comfort - Winter Heat Dstribution With radiator heating systems most of the heat is delivered through convection. Air passes over and through radiators causing uneven heat and temperature distribution due to circulation currents with cold draughts. Air movement spreads also dust, bacteria and pollen through the heat system and around the room. In addition, as radiators are usually located either below or close to windows, which are the weakest thermal element in the whole room, this increases heat loss and thermal discomfort. Radiant floor heating systems deliver heat throughout the room through thermal radiation. This allows an even heat distribution which increases thermal comfort. As Radiant Floor heating system heat your house from the floor up, they are almost aligned with the optimum heat curve. 7

5 Underfloor heating system Clean and Healthy Environment Unlike forced air heating, radiant floor heating has no drafts or fans blowing dust, dirt or allergens into the air. This is ideal for people suffering from allergies. In addition, humidity levels may be more easily controlled, thus helping reduce breathing problems. Because heat is radiated upward from the floor, it warms up all the other surfaces in the room and it prevents condensation on floors, walls and windows. Moreover, by maintaining a constant floor temperature (usually between C), your floor is warm to th e touch. This is very comfortable especially for smaller children who like to play on it. Thermal Comfort Today, radiant floor heating is the most efficient means of heat delivery in existence. It emits heat energy at low operating temperatures, thus providing comfort heating without equal. With radiant floor heating systems the surrounding surfaces are roughly the same temperature as your body surface and this helps you to feel comfortable with a good sense of well being. Key factors such as temperature and humidity control, even distribution of heat, vertical thermal gradient and direct contact with warm floor surfaces are fully satisfied. Radiant floor heating systems can be also used for cooling in summer to create a suitable microclimate in your house. 8

6 Underfloor heating system Fulfillment of physiological criteria There has been some initial scepticism about the benefits of UFH systems due to some negative physiological effects experienced by some users. These inconveniences have been caused by: - excessively high temperatures (e.g. 40 C) to matc h the high heat loss through the floor - use of zinc-plated steel pipe and wider pipe spacing - very high thermal inertia (pipes laid directly on the structural floor without insulation) - no adequate thermoregulation UFH systems have evolved a lot over the past few years thanks to the use of new materials in the production of serpentine pipes and better structure insulation. In addition, the introduction of specific requirements on energy efficiency and system dimensioning (ref. UNI EN 1264) and a more awareness of personal comfort/wellbeing as well as energy efficient behaviours have considerably contributed to make people choose heating systems working at lower temperatures. Aesthetics and Freedom in architectural design The lack of obtrusive radiators allows complete freedom of room design, decoration and layout. Valuable wall and floor space will be free to be arranged the way you want it, making a more pleasant environment to live in. In addition, UFH systems can be an efficient solution for buildings of historical and architectural interest, where special aesthetic concerns exist, since they can be installed without affecting the existing building structure.

7 Underfloor heating system Energy Efficiency Studies have shown that UFH systems are up to 10-15% more energy efficient. Because they operate at temperatures lower than usual (generally 1 C lower than radiator systems), whi le maintaining a uniform and climate in every room, heat loss and energy needs are dramatically reduced. Radiant energy emitted by the floor is progressively absorbed by each surface that becomes a secondary emitter. In this way, the warmth is evenly distributed over the whole room. Lower operating temperature contributes also to avoid wasted heat above head height and to reduce heat losses in the water distribution system, making for significant savings on fuel costs. Energy efficiency may be increased by using alternative heat sources such as solar panels, heat pumps and condensing boilers. Reduced running costs UFH systems are generally more expensive to install than radiator systems. However, the initial expense will be offset by more economical running costs due to lower heat temperatures. In addition, UFH systems improves thermal and acoustic insulation of loft and attic spaces, making for additional energy savings. 10

8 Underfloor heating system Versatility Underfloor heating systems can be used in almost any building applications: - residential applications - commercial/industrial applications - churches and places of cult - museums and historic buildings - fitness and wellness centres - schools and offices - renovations and extensions - greenhouses requiring homogeneous heat distribution - outside areas to prevent ice and snow build-up Some consider UFH systems not always the best choice for domestic applications due to a simplistic evaluation of the thermal inertia concept. Devices such as floating floor, temperature sensors and automatic regulators along with a careful design help reduce the amount of time the system needs to work at full performance. In addition, they allow the system to go into intermittent or modulated mode, so that the fluid temperatures may better adapt to the current heat load. In particular, the outside temperature sensor enables to modulate water temperature based on external heat loads, while on-off thermoelectric actuators open/close circuits depending on internal heat load. Further, it is advisable to use timing devices allowing to run the system according to user heating needs. Please note that, in the event of variable latent and sensible heat loads, the system may not satisfactorily match the requested parameters. Integration with existing systems UFH systems may be integrated with existing elements and devices, thus improving thermal and acoustic insulation thanks to the use of insulation panel and floating floor. 11

9 Underfloor heating system Heat output Heating mode The characteristic curve of an UFH system is the relationship between heat flow density and mean differential surface temperature. It is expressed by the following equation: q = 8,92 ( F,m i ) 1,1. where q (W/m 2 ): heat flux density 8,92: heat transfer coefficient W/(m²K) indicates the amount of heat transferred between surface and space and it depends on the room data such as air movement, room/surface temperature and position of the room F,m ( K): average floor surface temperature i ( K): nominal indoor operative temperature This relationship depends on the type of heat emitting surface (floor, wall or ceiling) and system operating modes (heating/cooling). Occupied zone 29 C Peripheral zone 33 C Bathrooms 35 C! "#$%& The higher efficiency of the system is Heat output at different room temperatures guaranteed with pipe spacing not exceeding cm and low t value. Generally, the difference between floor and room temperature is very small. However, even the slight change in room/surface temperature significantly Heat output per unit surface area [W/mq] alters the heat output which the UFH system is able to compensate accordingly (up to 100 W/m 2 ). Floor surface temperature ( C) 12

10 Underfloor heating system Cooling output Cooling mode The following equation expresses the cooling output of an UFH system used in cooling mode: q = 7 [ i s,m. ] where q (W/m 2 ): heat flux density 7: heat transfer coefficient W/(m²K) s,m ( K): average floor surface temperature i ( K): nominal indoor operative temperature Heat output per unit surface area at different floor temperatures With a temperature between 15 C and 30 C, the radiant heat transfer coefficient is 5,5 W/m 2 K. On the contrary, the convective heat coefficient depends on the type of heat emitting surface, air velocity and difference between surface temperature and surrounding air temperature (natural convection) and varies accordingly. The maximum heat output from an UFH system is 100 W/m 2 (heating mode) and 40 W/m 2 (cooling mode) for concrete floors. It can exceed 100 W/m 2 when sun rays directly hit the heat emitting surface Heat output per unit surface area [W/mq] Floor surface temperature ( C) 13

11 Radiant Panel System Radiant floor heating is by far the most effective heating method providing improved thermal comfort, greater energy efficiency and significant energy savings. It performs ideally when pipes carrying hot water at C are embedded in a concrete floor slab which acts as thermal mass diffusing heat evenly across the floor surface. The concrete slab is usually separated from the ground with an insulation layer preventing upward migration of soil moisture ( floating concrete slab), thus allowing to decrease thermal inertia. The floor temperature is typically maintained at C. This gives you a sensation of thermal comfort and well-being. Low temperature heat sources, temperature regulating devices and low operating temperatures (flow temperature is kept approx. at 40 C) help to minimize heat losses in the water distribution system. Most types of floor coverings can be laid over heated floors without being harmed by heat output such as ceramic, parquet, cotto tiles, carpeting, etc..the system shall be sized to operate properly even in presence of less favourable heat transfer conditions. Topklima Pentaklima Total heat output (radiant+convective) Heat output per unit surface area [W/mq] Floor temperature [ C] radiant heat convective heat total output 14

12 Thermal resistance values Standard UNI EN

13 Industrial applications Radiant underfloor heating is particularly suited for buildings having high ceilings, as it allows to decrease temperature while the height increases and to concentrate heat where it is really needed. This provides increased staff comfort and reduced air circulation and draughts. The substantial initial investment will be paid off in the long run through lower energy bills (up to 30% cost savings). Additional benefits are gained by the removal of air and strip heaters from walls and ceilings, thus freeing up more valuable space either for overhead cranes or storage or filling solutions (high shelving units). Heating pipes may be laid at a distance of 15cm. to the floor surface, so that they cannot be pierced when anchoring heavy equipment through anchor plugs. In the presence of foundations for heavy machinery, just run the piping system around them. Regarding the insulation layer under the concrete slab, it is difficult to determine a priori its maximum bearing load capacity. Generally, the mechanical resistance of an insulation layer is lower than that of concrete; for this reason, the insulation layer is often not used in industrial premises. 16

14 Industrial applications This results in higher heat loss through the floor and increased running costs. iklima provides you with polystyrene insulated panels able to withstand heavy loads without shrinking or deforming. Heating systems using welded wire mesh Heating sys. using radiant panels and Heating sys. using radiant panels fixing rails and anchor clips 17

15 Pipe layout Serpentine Pattern Serpentine patterns allow for higher temperatures along the perimeter areas of a room or zone (highest heatloss areas). It is mostly used for industrial buildings. Counterflow spiral pattern This pattern allows more evenly distribution of surface temperatures and closer pipe spacing thanks to fewer bend radius constraints. 18

16 @ Georg Fischer Pfci Srl Via degli Imprenditori 24/26 I Valeggio sul Mincio - Verona Phone Telefax pfci.ps@georgfischer.com Internet: