The pros and cons of chilled beams

The pros and cons of chilled beams Peter Clackett, Technical Director Skanska Rashleigh Weatherfoil William Booth, Operations Manager BSRIA

Agenda 09.30 Registration 10.00 Welcome & Introduction - Jo Harris, BSRIA 10.10 What, Why and How - Peter Clackett, Skanska Description and Application - Peter Clackett, Skanska Performance testing - William Booth, BSRIA Comfort break/coffee Performance testing continued - William Booth, BSRIA The good, the bad and the ugly - Peter Clackett, Skanska and William Booth, BSRIA Q&A - Chaired by Jo Harris, BSRIA 12.40 Networking Lunch Click on links above to access each presentation At the end of each presentation, click on link Back to Agenda

What, why, how many?

Chilled Beams What are they? They are a cooling device They are different from chilled ceilings These rely solely on radiant cooling (Output 50 to 55 watts per square metre) They are an alternative to both Fan Coil Units and VAV systems There are three kinds of chilled beams Active Chilled Beams can also be used for heating

Chilled Beams What are they? 1. Passive No reliance on primary air supply. They work entirely on radiant convection. (Output 130 to 170 watts per linear metre)

Chilled Beams What are they? 2. Active These rely on primary air supply to provide the induction required for performance. (Output 850 to 1400 watts per linear metre)

Chilled Beams What are they? 3. Multi Service These are active beams with the additional components (smoke detectors, lighting, sprinklers etc.) (Output 850 to 1050 watts per linear metre)

Chilled Beams The History Chilled Beams were developed in Norway in 1975 Originally used in Scandinavia Introduced to UK in 1990 s Now used world wide Device of choice for some Clients

How many?

ACB UK Market Data Provided by BSRIA s Worldwide Market Intelligence (WMI) Group Data comes from the HEVAC study Annual collection of a/c product sales Managed by BSRIA for a number of years with HEVAC/FETA s endorsement All data to be published in the UK Air conditioning study next month buy from WMI Author David Garwood (available over lunch)

Market For Chilled Beams & Ceilings* UK market reduced over last couple of years Many major projects were shelved or put on hold Leading suppliers now seeing signs of improvement Some major projects now moving forward 2012 sales were for universities, hospitals and labs plus a few offices and police stations * Data provided by WMI, BSRIA

UK Fan Coil Market* Highly engineered product in UK market But.. Highly price driven Customers of fan coils look at : First price Second thermal performance Third acoustic performance * Data provided by WMI, BSRIA

Chilled Beams vs Fan Coil Units Active chilled beams main substitute product for FCUs Conversely, ACB players fighting back against threat of FCU through marketing: Demonstrating how ACB can be a suitable replacement for FCU Placing emphasis on: Energy efficiencies Long life expectancy Low maintenance Occupant comfort * Data provided by WMI, BSRIA

Market Data 2010-2012* Item 2010 2011 2012 Market ( M) Active Chilled Beams 9.7 9.9 8.0 Fan Coils 26.6 27.1 23.7 Variable Air Volume 2.3 6.7 5.3 Volume ( Units) Active Chilled Beams 34,500 33,400 27,000 Fan Coils 51,500 54,000 46,800 Variable Air Volume 5,500 13,300 13,500 Unit price Active Chilled Beams 281 298 296 Fan Coils 517 502 506 Variable Air Volume 418 504 393 * Data provided by WMI, BSRIA

2012 Market Data* 2012 Market Share ( M) Variable Air Volume, 5.3 Active Chilled Beams, 8.0 Variable Air Volume, 13,500 2012 Market Share (units) Active Chilled Beams, 27,000 Fan Coils, 23.7 Fan Coils, 46,800 2012 Unit Price Variable Air Volume, 393 Active Chilled Beams, 296 Fan Coils, 506 * Data provided by WMI, BSRIA

70% Market 2012 FCU Market Players (Ranked By Value) Ability Projects Diffusion Dunham Bush TEV limited Trox * Data provided by WMI, BSRIA

20% Market 80% Market 2012 ACB Market Players (Ranked By Value) Trox Frenger Systems (Lindab) Halton SAS international Krantz Swegon Flaktwoods LTI Advanced systems Technology (Keifer brand) Waterloo Air products Others * Data provided by WMI, BSRIA

Back to Agenda

Description and application

Active Chilled Beams - Considerations Still requires central bulkhead or similar for services (Supply Duct, Extract Duct, Chilled Water Pipework, Controls etc.) Careful control of primary supply air temperature required to prevent perception of cold draughts Chilled water temperature needs accurate control

Active Chilled Beams - Considerations Performance of the whole space needs to be evaluated The air patterns are very hard to predict Air distribution throughout the space is load dependent Computer modelling does not give the true air movement answers You MUST understand the product, how it works and how it integrates to its environment

Active Chilled Beams - Considerations Heating application requires careful design It can be counter intuitive Full mock-up of partial areas is the best solution to understand the product

Video not available in pdf. format

Active Chilled Beams - Advantages Cheaper to buy Low Maintenance One Fix device Does not require secondary ductwork/grilles etc. Only require simple controls On/Off is adequate for cooling Variable Self Limiting Output No condensate drainage required

Active Chilled Beams - Advantages Supply conditioned air to the space Large induction ratios Fully mixes the air within the space Very slow air velocities within the occupied zone Multi service beams allows ancillary services to be concealed

Active Chilled Beams - Advantages Works well when combined with other cooling sources Requires full scale mock-up testing to ensure that they do not interact Very quiet product Can be visually pleasing

Active Chilled Beams - Disadvantages Not liked by letting agents Not flexible enough No energy allowances under Building Regs. (FCU s allowed 0.6w/(l/s) - FAVAV allowed 1.2w/(l/s)) Normally requires higher system static pressures Airflow may be greater than required for occupancy

Active Chilled Beams - Disadvantages Poor chilled water temperature control can lead to indoor rain May require sound masking (pink noise) to maintain privacy levels Requires careful co-ordination to get the solution right

Back to Agenda

Performance testing

ACB Definitions Reference temperature: return air onto beam (usually underside in active beams) Mean water temperature: average of water into and out of beam Difference gives indication of cooling potential: no difference means no cooling should happen BS EN 15116:2008 Ventilation in buildings. Chilled beams. Testing and rating of active chilled beams

Schematic of test chamber

Performance Testing BS EN 15116:2008 Internal heat supply method Heat sources within chamber (DIN men) External heat supply method Heated walls (same concept as radiator test room) General principle of a calorimeter with steady state boundary conditions and 60 min steady state data

Performance Testing BS EN 15116:2008 Temperature difference ΔΘ = Θ r θ w Θ r = reference air temperature Θ w = mean cooling water temperature q p = primary air flow rate 3 steady state conditions at ΔΘ = 6, 8 and 10K with constant q p Repeat at ΔΘ = 8K nominal with q p at 80% and 120% to determine influence of primary air on thermal performance Repeat all five at half the nominal water flow rate

Performance Testing BS EN 15116:2008 Performance follows the form of P w = P k * ΔΘ m Where P w is waterside cooling capacity P k is specific cooling capacity m is an exponent Alternatively, P k = P w / ΔΘ m Also, P k = A * q p n A is a characteristic constant n is an exponent

Example Results

Water side duty ( W) Water side duty (W) 1000 900 800 700 600 500 400 300 200 100 0 P w (const q p ) 0 5 10 15 Mean Temperature Difference (K) y = 77.233x 1.0598 R² = 1 Pw (const qp) Power (Pw (const qp)) 1000 900 800 700 600 500 400 300 200 100 0 P w (var q p ) 0 20 40 60 80 Primary airflow rate (q p ) (l.s -1 ) y = 182677x -1.394 R² = 0.9777 Pw (var qp) Power (Pw (var qp))

Example graph of Capacity against temperature difference for three water flowrates

Same as previous showing passing through zero

Different beam same graph shape

Airflow vs. flowrate of air

Water side pressure drop vs. flowrate

Performance Testing Performance follows the form of P k = P w / ΔΘ m P k = A * q p n Report the nominal cooling capacity P N (at ΔΘ n = 8K) Optionally, cooling capacity as fn(globet- Θ w ) or fn(roomt - Θ w ) Selection guides and tables will include throw, noise figures, water and air side pressure drops as well as nozzle selections, heating coil options, etc..

Ball Park Numbers 1200-1500mm Waterside Cooling 0.02 to 0.10 l/s 14-16 C supply with 1-3K rise Waterside Heating (100-300 W/m) 0.01 to 0.04 l/s 35-45 C inlet with drop of 5 to 15K Airside Cooling/Induction 10-60 l/s primary air at 18 C for roomt 24 C

Back to Agenda

System performance testing

Physical modelling Predicting and measuring real life situations Achieving the correct results first time Prove beforehand that the systems and products will meet the necessary specifications Water supply (from chiller) Conditioned air Client s ventilation system AHU Ceiling void Glass window Viewing chamber Floor tiles/carpet Floor void Chamber wall Adjacent chamber Adjustable walls Control room Insulated floor ( 400 mm)

Physical modelling Constructing a full size representation of the proposed design for a specific part of a building interior. Full simulation of external conditions Internal loads Comprising lighting Small power and people Room furnishing and office equipment layout Fully working HVAC system.

Validation process Room air movement Gas tracer tests Salt tests Supply Chamber Ceiling Ceiling void Smoke tests Fans/Air conditioning system Ceiling tiles Wall Floor tiles Adjacent chamber CFD Floor extract Back passage Extract Floor void Control room Airtightness Mock-up construction Design

Full size mock-ups Mock-ups of any ventilation system; chilled beam configuration, offices, hospital rooms, cold cabinet testing Thermal comfort analysis Temperature and humidity readings Airtightness tests Heat load simulation (Small load, occupancy, solar load) Anemometry readings ( air speed and temperatures) Gas tracer tests Special components commissioning (pressure stabilisers, ventilation grilles, floor grilles) Thermal imaging Smoke tests

Offices Data centres Libraries Chilled beams Cold cabinets Hospitals

Real site vs mock-up

Job A

Animation Animation not available in pdf. format

Smoke test Video not available in pdf. format

Job B

Example of discharge profile

Job C

Example of ductwork and ceiling

Calc Induced Flow (l/s) Example of Pressure test Full pressure test - Beam 1 type 2 (16 Sep 05) 50.00 2.50 45.00 40.00 35.00 y = 0.0366x + 1.0705 R 2 = 0.8431 2.00 30.00 25.00 y = 2.2863x - 9.3206 R 2 = 0.9933 1.50 20.00 1.00 15.00 10.00 0.50 5.00 0.00 0.00 0.00 5.00 10.00 15.00 20.00 25.00 30.00 Primary Flow (l/s) Calc Ind Flow Ratio Linear (Calc Ind Flow) Linear (Ratio)

Example of average parameters A PARAMETER REQUESTED VALUE AVERAGE DURING TEST SUPPLIED VALUE Water supply temperature ( C) 14.0 13.9 Water return temperature ( C) To be recorded 15.9 Water flow rate (l.s -1 per beam) 0.039 0.039 Water flow rate (l.s -1 all beams) N/A 0.353 Cooling duty (10 beams) (W) N/A 2958 Fresh air supply temperature at point of entry to the test rig ( C) 18.0 18.1 Extract temperature ( C) To be recorded 23.5 Air flow rate (l.s -1 ) 90 97 Fresh air cooling duty (W) N/A 583 Total cooling (W) N/A 3541 Electrical load (W) Start End Solar load simulated with 15 1416 1418 1440 wall mounted heated mats Occupancy (6 DIN Men simulating 7.5 people) 675 685 698 Small power gain 844 830 835 Lighting gain 405 419 419 Total electrical load 3340 3352 3392 Total electrical load (Average) 3340 3372 Imbalance (W) 169

Example of parameters PARAMETER VALUE Fresh air supply volume 60 l.s -1 Fresh air supply temperature 19.0 C Beam chilled water supply 0.226 l.s -1 volume for perimeter test Beam chilled water supply 0.274 l.s -1 volume for core test Chilled water supply 14.0 C temperature Illuminance As produced by integral lighting system

Example of average parameters B PARAMETER AVERAGE SUPPLIED VALUE REQUESTED VALUE Fresh air flowrate 64.1 l.s -1 60 l.s -1 Extract flowrate 62.6 l.s -1 60 l.s -1 Fresh air supply temperature 19.0 C 19.0 C Extract temperature 23.4 C N/A Altrium roof load emitted into room (simulated with 3 wall mounted heat mats) 510 W 525 W Core people gain (simulated with 6 600 W 600 W standard DIN men) Core small power gain (simulated with 1.69 kw 1.821 kw 4 standard PCs and 7 floor heat mats) Lighting gain 905 W As produced by integral lighting system Total heating gain (perimeter, core and lighting) 3.705 kw 2.946 kw plus lighting gain Chilled beam water flow temperature 13.9 C 14 C Chilled beam water return 16.4 C N/A temperature Chilled beam water flowrate 0.28 l.s -1 0.274 l.s -1

Parameter Average cooling during Test 3 (kw) Chilled beam cooling effect 2.93 Air cooling effect 0.34 TOTAL COOLING 3.27 kw

Back to Agenda

Ugly Duckling or Hidden Swan?

Chilled Beams - Advantages Cheap to Buy and Maintain Simple principals Simple Controls Give a well conditioned space Very adaptable Quiet Energy Efficient

Chilled Beams - Disadvantages Not always popular Lack of application knowledge can restrict use Low noise may be an issue Integration into environment may not be as simple as it seems - Can be hard to get right

Questions and answers

Q&A Session Adaptive temperature theory Turbulent water flow Uneven load distribution Load location fighting the beam Windows impinging on active beam lengths Control strategy

Back to Agenda