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Sustainability in Ceilings
- 1. Using Phase Change Materials in construction for a more sustainable built environment Presented by For further information please contact Jeremy Sumeray, Head of Sustainability, Armstrong Building Products jsumeray@armstrong.com 07833 444510
- 2. Help you to be better able to understand where and how Phase Change Materials can be used to create a more energy efficient and comfortable environment
- 3. 3 When to consider Phase Change Materials As part of a low-carbon energy strategy for new build and refurbishments Improving thermal comfort for the occupants Overheating spaces with high demand for air conditioning 12 6 39 ampm OUTININ In the hot afternoon, the PCM cassettes suck up the heat and keep the room pleasantly cool.
- 4. 4 PCM needs to be cooled in the evening to re-set Best suited for classrooms, offices, retail, healthcare 12 6 39 ampm OUTININ In the evening, the PCM cassettes release the heat and the room is purged ready for the next day When to consider Phase Change Materials
- 5. 5 PCM – thermal mass effect HEAT ENERGY Tp Latent Heat SOLID LIQUID Equivalent thermal mass 3cm plaster, containing 30% PCM 14cm concrete 18cm bricks PCM’s provide lightweight thermal mass
- 6. 6 PCM Theory – thermal mass effect 18 20 22 24 26 28 30 32 34 10/0700:00 10/0712:00 11/0700:00 11/0712:00 12/0700:00 12/0712:00 13/0700:00 13/0712:00 14/0700:00 14/0712:00 15/0700:00 Without PCM With PCM Temperature°C Rule of thumb: ≥3kg/m² floor space Comparison Air Temperatures [°C] Comfort Zone Stabilized Date and Time
- 7. 7 BASF Micronal Picture: BASF Picture: BASF Microcapsules as packaging Huge surface/volume-ratio -> fast heat transfer Paraffin core Polymer shell Polymer coating Wax Melting Point: 23C / 26C
- 8. 8 • Fire Reaction – Protect PCM from fire to achieve minimum performance • Cutting – Do not cut PCM cassettes • Health Concerns – As this PCM is microencapsulated it causes no health concerns. The PCM will not leak out of the product and the plasterboard it is implanted in can be recycled in existing streams. • Installation – Care when handling and Grid strengthening • Maintenance - Standard cleaning procedure and no ongoing maintenance to the PCM Health and Safety Considerations PCM CassetteAcoustical tile
- 9. 9 PCM cassettes absorbs heat and stabilises room temperature 26oC 22oC A cooler surface temp. Also improves the thermal comfort of the space 15 17 19 21 23 25 27 29 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 26oC +/- 2.0oC Standard ceiling 22oC +/- 1.0oC PCM ceiling Hour of the day Surface 1 Ch11 [C]
- 10. 10 PCM ceiling tiles with Natural Ventilation Belvoir High SchoolPCM ceiling tile
- 11. 11 e-stack System: Hot summer day ©Breathing Buildings Ltd. High Summer – Downwards displacement ventilation Minimum ventilation rate
- 12. 12 Belvoir School – PCM test data ©Breathing Buildings Ltd. • Night time (5pm-8am) : e-stack ventilating and façade windows open • Day (9am to 3.30pm): no ventilation, heat addition 2.1kW per room PCM room (Room 7) cooler than standard room (Room 8) during day
- 13. 13 Case Study Add quote here Test Conditions Structure: Insulated Thermal Test Chamber HVAC System: 1.Displacement ventilation; 2.Overhead air; 3.Overhead air ducted return Location: BSRIA , Bracknell, UK Room Size: 16 m2 Ceiling Coverage with CoolZone: 0, 30, 57 % Thermal Storage: 0, 662, 1,260Wh Applied Cooling Load: 30, 60 W/m2 Air Circulation Rate: 2.5, 4.1, 11.1 l/s m2 Purge Temperature: 14, 18 0C Displacement Ventilation System • 662Wh of thermal storage delayed the operation of the air conditioner by 1:20 hours with a 30 W/m² load • 1,260Wh delayed this by 4:27 hours. • The PCM tiles typically reduced temperature variations on the ceiling to +/- 1ºC.
- 14. 14 It is a passive solution, and maintenance free PCM Plays a Role in Supporting High-Performing Real Estate Reduces Air Conditioned energy usage by 25 to 50 [%] Offset daytime energy using low energy strategies at night – load shifting Reduces temperature variations, improving thermal comfort Improves energy performance of the building (DECs & CRC) Better lettable rates for low energy buildings Future proof - can add tiles at a later date Flexible Long term portable asset Easy to incorporate into existing buildings Can be moved within the room or moved room- to-room Can locate tiles where needed to deal with high heat-load
- 15. 15 Summary Direct reduction in energy consumption Improved thermal comfort Avoid cold draughts, air dumping and peak summertime temperatures A passive but controllable solution for ventilation and cooling
- 16. 16 ANY QUESTIONS? For further information please contact Jeremy Sumeray, Head of Sustainability, Armstrong Building Products jsumeray@armstrong.com 07833 444510
Notas do Editor
- This presentation is Armstrong’s RIBA accredited CPD presentation entitled… ‘Using Phase Change Materials in construction for a more sustainable built environment’ …and is presentation by Add: NameAdd: Title
- Phase Change materials are not a new technology, they have been used in various forms since the 1970’s. It is only in recent years that the focus on sustainability and advances in the durability and commercialisation of PCM’s that they have started to be used in construction products.Phase Change materials help to lower energy consumption within a building and maximise the efficiency of a buildings ventilation system.It is important to note that Phase Change materials are not suitable for all project situations, this presentation will outline the limitations and requirements when using PCM in a construction product.
- PCM can be used in Active and passive systems when designed in conjunction with the HVAC system to maximize efficiency. From natural ventilated spaces to integrated chilled ceilings most types of HVAC system can be made more efficient. PCM can be used to offset the requirement of air conditioning, therefore saving on cooling energy, and energy costs.PCM optimizes use of regenerativecooling and heating sourcesPCM should not be used as a replacement for insulation, it acts as a thermal storage unit, rather than blocking out or containing thermal energy.NoGoPCM’s should not be used on exterior walls, the solar gain via the walls greatly reduce capacity of the PCM, and thus leave an inefficient system.PCM’s cannot be added to existing “Active” cooling or heating easily. These systems can be adapted when the design of the cooling or heating incorporates PCMPCM cannot replace air conditioning to manage internal humidity, only thermal comfort.
- There are different ways of creating the purge strategy to cool the PCM in the evening. The most sustainable is to use the cool night time air from outside the building.
- PCM’s provide lightweight thermal massTo create the same thermal capacity as 3cm plasterboard containing 30% PCM you will need 14cm of concrete, or 18cm of bricks.PCM allows high thermal mass properties to be added to lightweight construction, which could not support bricks or concrete.By using light weight construction it is possible to reduce building cost and running cost of the project.
- In this graph the red line shows the temperature fluctuation throughout an office space over a week without an installation of PCM material.The Blue line shows the same fluctuations over the week but this time with PCM materials added to the office space.The use of PCM material adjusts the thermal comfort of the room. The very high temperatures of 32°C are not reached with PCM, as the excess heat is stored within the product. This heat is then released at night when the room cools down, so the room does not reach the low temperature of 18°C.This process and ability to store excess heat energy creates an improved temperature stability throughout the working day. The temperature drop in the evening has the effect of resetting the PCM for the next day or cycle.PCM is trapping heat from room during the day and recrystallization as the temperature drops helps to recharge the PCM
- Waxes, not water, for construction Unfortunately water with its temperature transitions at 0C and 100C (32 and 212F) is not suitable for use in construction. In such situations waxes are used, whose melting points can be flexibly adjusted according to the application. BASF’s solution for safely inserting latent heat stores into building materials of all kinds is microencapsulation. Tiny globules of wax 2 to 20 microns in diameter are coated with a layer of extremely hard plastic. These microcapsules are completely sealed, safe to process and free of formaldehyde. In addition, the resultant materials are well suited for further treatment – they are impervious to grinding, drilling, cutting, etc. since their small size makes them virtually indestructible.The encapsulation process also protects the wax in its very pure form, meaning the high heat storage capacity of 110 kJ/kg is permanently guaranteed. Measurements at the Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg have confirmed this. In principle it can be manufactured to any switching temperature. BASF’s Micronal® DS 5000 X absorbs the ambient heat energy at around 26C (79F). This temperature has been confirmed by computer simulations to be optimal for passive summer heat reduction in buildings. A material with a switching temperature of 23C (73F) is also available for situations where PCM is to be used as part of a climate control concept.
- Fire ReactionAs PCM’s are oil based waxes there are obvious concerns about performance in a fire. Containing the PCM in a metal ceiling tile helps to protect it from flames and also stops some smoke and droplets to escape.When using PCM plasterboards a second layer of plasterboard must be used to give the fire reaction protection. Any cuts into the PCM boards should be sealed with an aluminium tape.CuttingFor the metal ceiling PCM cassettes only full tile modules should be used. The product should not be cut for perimeter cuts or have holes cut into it for services. This will reduce the fire reaction performance. Tiles that have been cut should not be used in the ceiling, they can be recycled easily in main stream recycling streams for steel and plasterboard.Health concernsAs the PCM is microencapsulated there are no concerns about the material leaking out of a product, hence why the product can easily be recycled.InstallationThe PCM cassettes are heavy panels some weigh up to 9Kg each. Care must be taken when moving them around and when installing into the grid system.The cassettes can be installed into a standard suspended ceiling grid, however additional supports may be required. Typically hangers at 1m centres and main runners at 600mm centres.MaintenanceCleaning of the PCM cassettes is the same as for any metal ceiling tile, a damp cloth or a duster in most instances. Mild detergent for stubborn stains.The PCM itself needs no maintained as it is a passive solution and will work continuously for over 30 years.
- A standard metal ceiling tile warms up as the temperature of the room increases, this is seen by the green and red colours on the tile on the left.With the PCM insert, as the room temperature increases the heat is pulled through the metal tile and into the PCM.The surface temperature of the PCM tile remains cool. This can be seen by the blue colour of the tile on the right.This continues until the heat capacity of the unit is used up (the wax has changed completely from solid to liquid) After this time the room will continue to heat up if the heating load on the room remains at the same level.The graph shows the difference between a standard ceiling and a PCM ceiling throughout one day.For the standard ceiling the room heats up with the heating load of a typical working office (people, computers, printers, lighting etc) At a certain point the air conditioning is triggered. This then cools the room and shuts off, the room continues to heat and the air conditioning comes on again.This cycle continues until the heat load on the room is removed (the office closes for the night)With the PCM ceiling the room does not overheat, any excess heat above the set point of 24°C is absorbed by the PCM and the air conditioning is not triggered. An even comfortable temperature is maintained and the energy and therefore cost of that energy associated with the air conditioning is saved.In the cool evening in the absence of the heating load the pcm tiles gradually cool, return to solid form and drop the heat energy they have stored back into the room. This means that the room is not too cool first thing in the morning but at a comfortable working temperature and the PCM tiles are reset for another working day.
- Some Conclusions When the rooms were sealed during the day and heated, the room containing PCM ceiling tiles was generally 2 degCcooler than the room with normal ceiling tiles. This was the case for heat loads of both 2 and 4kW heat loads per room. When the interior temperatures did not cool below 23degC at night, the room with PCM tiles was still cooler than the room with normal tiles the following day. This suggests that i) the PCM had managed to part freeze even though the temperature hadn’t dropped below 23degC and/or ii) the thermal mass of the PCM tiles provides some buffering, in addition to its latent cooling.
- Overhead Air supply with UnductedReturnSystemWith 30% coverage, PCM can be successfully purged with airflow rates typically used with these systems.Purge times are affected by the amount of energy stored in the ceiling (662Wh), purge air temperature and purge air velocity. Lowering the purge temperature from 18ºC to 14ºC decreased the purge time by 3:07 hours.