Effect of acoustical canopies and fans on acoustical and chilled ceiling performance Fred Bauman and Caroline Karmann Center for the Built Environment, University of California, Berkeley Golden Gate and Redwood Empire ASHRAE Chapter Meeting March 10, 2016 HVAC Systems Center for the Built Environment ASHRAE Golden Gate Chapter March 2016
Background: Exposed concrete Radiant spaces shows lower occupant satisfaction with acoustics Exposed concrete is highly sound reflective Effect of acoustical canopies on: - Cooling capacity of radiant ceiling - Acoustical reverberation Concrete ceiling (Brower Center) Image: Tom Griffith Acoustical canopies Image: CBE, 2011 Armstrong Acoustical tiles Image: Armstrong Taken from the final report of CEC PIER Buildings Program (No. 500 06 04) 2 Center for the Built Environment March 2016
Background: Adding air movement CBE study 2013: Use of a fan to increase convective heat exchange between the acoustical canopies and the radiant ceiling Method: CFD study Results: up to 50% increase of cooling capacity of the radiant ceiling with coverage and fan Section of the system studied Results: air velocity mapping (fan blowing upward) 3 Center for the Built Environment March 2016
Project overview Objective: Cooling and acoustical performance of a radiant chilled ceiling with acoustical canopies and fans Methods: Joint lab study Cooling capacity tests (at Price) Acoustical tests (at Armstrong) Schematic section of a radiant slab Funding EPIC grant In-kind and material support from: - Price Industries - Armstrong World Industries - Big Ass Fans Schematic section of a radiant slab with acoustical canopy 4 Center for the Built Environment March 2016
Test configurations: Acoustical coverage 0% (no canopies) 16% (2 canopies) 32% (4 canopies) 48% (6 canopies) 64% (8 canopies) 5 Center for the Built Environment March 2016
Test configurations: Fans No fan (reference case) Ceiling fan blowing up and down between the canopies Small fan hidden above the canopies Central ceiling fan Small fans hidden above the canopies 6 Center for the Built Environment March 2016
Acoustical testing 7 Center for the Built Environment March 2016
Experimental set-up Objective: Determine the minimal acoustical coverage for acceptable acoustics quality Approach: Acoustical tests in a reverberant room (Accredited by NVLAP) Reverberant room, NRC testing Experimental set-up Armstrong canopies tested upside down Plenum 16, Spacing 6 Arrays of 4, 6, 8, and 9 canopies Armstrong Soundscapes Shapes canopies 8 Center for the Built Environment March 2016
Results: measured absorption 78 [Sabin] 4 Canopies 64 [ft 2 ] 33 [%] Cover 109 [Sabin] 6 Canopies 96 [ft 2 ] 49 [%] Cover 139 [Sabin] 8 Canopies, 128 [ft 2 ], 65 [%] Cover 147 [Sabin] 9 Canopies, 144 [ft 2 ], 73 [%] Cover Sabin, unit of sound absorption, 1 [ft 2 ] of 100% absorbing material = 1 imperial Sabin 9 Center for the Built Environment March 2016
Results: reverberation time 10 Center for the Built Environment March 2016
Cooling capacity testing 11 Center for the Built Environment March 2016
Experimental set-up Hydronic test chamber Room 14 x 14 x 10 ft 8 in. thick R40 insulation Radiant panels (8.2 ft ceiling height) EN14240 compatible (standard for cooling capacity testing of radiant panels) Experimental set-up Simulated workstations Ceiling combinations (fans/canopies) 12 Interior view of the hydronic test chamber from Price, Winnipeg, MB Center for the Built Environment March 2016
Location of the 2 measurement trees Plan of the chamber 13 Center for the Built Environment March 2016
Internal loads simulated through workstations 14 Center for the Built Environment March 2016
Ceiling fan variants 52 inch Blowing up Blowing down Small fans variants 8 inch Central ceiling fan Low speed Medium speed Small hidden fan (located above the canopy) 15 Center for the Built Environment March 2016
16 Center for the Built Environment March 2016
Results: Canopies without fans Change in cooling capacity radiant ceiling Change in cooling capacity [%] 130% 120% 110% 10 100% 0 10 90% 20 80% Small fans medium Ceiling No fan fan up No fan No fan Small fans low Ceiling fan down No canopies and no fan (reference) 5% uncertainty (95% confidence) 30 70% 0 0% 16 16% 32 32% 48 48% 64 64% Acous cal Acous coverage cal coverage [%] 17 Center for the Built Environment March 2016
Results: Canopies with ceiling fan Change in cooling capacity [%] Small Central fans medium fan up Ceiling No fan up Central No fan down Small fans low Ceiling fan down 30 20 10 0 10 20 30 0 16 32 48 64 Acous cal coverage [%] 18 Center for the Built Environment March 2016
Results: Canopies with small fans Change in cooling capacity [%] Small Small fans medium fan medium Ceiling fan No up fan Small No fan fan low Small fans low Ceiling fan down 30 20 10 0 10 20 30 0 16 32 48 64 Acous cal coverage [%] 19 Center for the Built Environment March 2016
Results: All variants Change in cooling capacity [%] Small Small fans fans medium medium Ceiling Ceiling fan fan up up No No fan fan Small Small fans fans low low Ceiling Ceiling fan fan down down 30 20 10 0 10 20 30 0 16 32 48 64 Acous cal coverage [%] 20 Center for the Built Environment March 2016
Results: Impact of fan energy use No fan no coverage 32% coverage 48% coverage Change in cooling capacity Change in loads Ceiling fan blowing up no coverage 32% coverage 48% coverage Small fan medium no coverage 32% coverage 48% coverage? 15 10 5 0 5 10 15 20 Change in cooling capacity and loads [%] 21 Center for the Built Environment March 2016
Results: Key take-aways from thermal comfort analysis MRT and T air are about the same - No fan and no canopies: 1º C - Max difference measured: 1.2º C - MRT gets higher than T air w/ fan on Stratification of 1.5º C (feet/head) when no fan and no canopies Fans reduces stratification Air movement in the occupied zone: - Ceiling fan DOWN: 0.25-1 m/s - Ceiling fan UP: 0.25 m/s 22 Center for the Built Environment March 2016
Summary Only minimal reduction of the cooling capacity of the radiant chilled ceiling with canopies With fans it is possible to increase the cooling capacity (e.g. 25% increase based on EN14240 additional testing) Results are for cooling (heating case may be different) Use of fans may improve control of thermally massive radiant slabs Concrete ceiling (Brower Center) Image: Tom Griffith Acoustical canopies Image: Armstrong 23 Center for the Built Environment March 2016
Acknowledgment Paul Raftery, Stefano Schiavon, Hui Zhang Center for the Built Environment, UC Berkeley Mike Koupriyanov, Harmanpreet Virk, Jared Young, Tom Epp, Jerry Sipes Price Industries Bill Frantz, Kenneth Roy Armstrong World Industries 24 Center for the Built Environment March 2016
Questions? Fred Bauman fbauman@berkeley.edu Caroline Karmann ckarmann@berkeley.edu CBE website www.cbe.berkeley.edu CBE EPIC radiant project website www.cbe.berkeley.edu/research/optimizing-radiant-systems.htm 25 Center for the Built Environment March 2016