Culminating Project Fire Protection and Life Safety Engineering Analysis Fire Protection Engineering California Polytechnic State University Center for Science and Mathematics Cal Poly San Luis Obispo, CA Orelvis Gonzalez March 20 th, 2015
Presentation Outline Building Characteristics and Regulatory Framework Prescriptive-based Structural Fire Protection Flammability Assessment. Means of Egress Fire Alarm and Detection Systems Fire Suppression Systems Performance-based Egress Analysis and Tenability Conditions Assessment RSET vs ASET Analysis Conclusions and Recommendations
Building Characteristics Project Name Location Const. Type Total Floor Area Actual Height Center for Science and Mathematics (CSM) California Polytechnic State University, San Luis Obispo, CA 1B, Fire-Resistive 188,372 G.S.F. 108 ft. Defined Height Building Occupancy 64 ft. Non High-rise building Group B, Business Occupancy High-Rise Building: Having floor used for human occupancy located more than 75 feet above the lowest floor level having building access
Building Characteristics
Building Characteristics Fire Department access provided within 150 feet of all portions of the building. (IFC, 2007, Section 503.1.1) South facing side require approval from the fire code official.
Regulatory Framework Main Applicable Codes California Building Code (CBC), 2007 Ed. California Plumbing Code (CPC), 2007 Ed. California Mechanical Code (CPC), 2007 Ed. National Electric Code (NFPA 70), 2005 Ed. Life Safety Code (NFPA 101), 2006 Ed. California Fire Code (CFC), 2007 Ed. National Fire Alarm Code (NFPA 72), 2007 Ed. NFPA 13, Standard for the Inst. of Sprinkler Systems, 2007 Ed.
Prescriptive Structural Fire Protection CONSTRUCTION TYPE 1B, Fire-Resistive The building elements are not combustible material (IBC, 2007, Section 602). FIRE-RESISTANCE RATING REQUIREMENTS FOR BUILDING ELEMENTS (CBC, 2007 Table 601) Building Element FIRE-RESISTANCE RATING (Hours) Primary Structural Frame 2 * Bearing Walls (Exterior) 2 Bearing Walls (Interior) 2 * No Bearing Walls (Interior) 0 Floor Construction and Associated Secondary Members 2 Roof Construction and Associated Secondary Members 1 * 1-hour permitted where supporting a roof only
Prescriptive Structural Fire Protection CONSTRUCTION TYPE 1B, Fire-Resistive The building elements are not combustible material (IBC, 2007, Section 602). FIRE-RESISTANCE RATING REQUIREMENTS FOR BUILDING ELEMENTS (CBC, 2007 Table 601) Building Element FIRE-RESISTANCE RATING (Hours) Primary Structural Frame 2 * Bearing Walls (Exterior) 2 Bearing Walls (Interior) 2 * No Bearing Walls (Interior) 0 Floor Construction and Associated Secondary Members 2 Roof Construction and Associated Secondary Members 1 * 1-hour permitted where supporting a roof only
Prescriptive Structural Fire Protection Six-level (5 stories) central structure devoted to offices and student spaces with wings on either side that house classrooms and laboratories http://www.flickr.com//photos/calpolyscience/sets/72157628917516905/show/ I (or W) shapes fire proofed with SFRM Girders and beams Columns Reinforced C. walls in levels 1 and 2
Prescriptive Structural Fire Protection BUILDING OCCUPANCY Uses and Occupancies Group B, Business Occupancy An occupancy used for the transaction of business other than mercantile (NFPA 101-2006, Section 6.1.11.1) Lobbies/Lecture - Occupant Load >50: (A-3) Office: (B) Conference Rooms - Less than 50 occupants: (B) Laboratories: (B) Electrical and Telephone Data: (S-2) Mechanical Rooms: (S-1) Storage: (H-3 and S-2)
Prescriptive Structural Fire Protection REQUIRED SEPARATION FOR OCCUPANCIES (CBC, 2007 Table 508.3.3) OCCUPANCY FIRE-RESISTANCE RATING (Hours) B A 1 B H-3 1 B S-1 N B S-2 1 S-1 H-3 1 S-1 S-2 1 N: No separation requirement
Prescriptive Structural Fire Protection REQUIRED SEPARATION FOR OCCUPANCIES (CBC, 2007 Table 508.3.3) OCCUPANCY FIRE-RESISTANCE RATING (Hours) B A 1 B H-3 1 B S-1 N B S-2 1 S-1 H-3 1 S-1 S-2 1 CBC 405.5 Exception 3: A Fire Barrier is not required between the atrium and the adjoining spaces of any three floors of the atrium provided such spaces are accounted for in the design of the smoke control system.
Prescriptive Flammability Assessment Max. Flame Spread Classification (Class) Interior Finishes : (CBC, 2007 Table 803.5) Group Exit enclosures and exit passageways (Sprinklered) Corridors (Sprinklered) Rooms and enclosed spaces (Sprinklered) A-3 B B C B B C C S-1 C C C S-2 C C C Class B: Flame Spread index 26-75, smoke developed index 0 450 Class C: Flame Spread index 76-200, smoke developed index 0-450
Prescriptive Mean of Egress At least 3 exits required (NFPA 101, 2006 Section 7.4.1.2) Occupant Load more than 500 but no more than 1000 At least 2 exits required (NFPA 101, 2006 Section 38.2.4.1) Occupant Load less than 500. No less than two separate exits shall be provided on every story.
Prescriptive Mean of Egress Travel distance shall not exceed 300 ft. (NFPA 101, 2006, Section 38.2.6.1)
Prescriptive Mean of Egress Structural Fire Prot. Level 1 15 ft 2 /person 300 ft 2 /person 15 ft 2 /person TD = 149 OCCUPANT LOAD: 703 EXITS DOORS EXITS STAIRS CORRIDORS ELEVATORS/LOBBIES BUSINESS ASSEMBLY STORAGE HAZARD TRAVEL DISTANCE At least 3 exits required: Occupant Load more than 500 but no more than 1000 Travel distance must not exceed 300 ft. Business
Prescriptive Mean of Egress Structural Fire Prot. Level 2 OCCUPANT LOAD: 523 TD = 184 EXITS DOORS EXITS STAIRS CORRIDORS ELEVATORS/LOBBIES BUSINESS ASSEMBLY STORAGE HAZARD TRAVEL DISTANCE At least 3 exits required: Occupant Load more than 500 but no more than 1000 Travel distance must not exceed 300 ft. Business
Prescriptive Mean of Egress Structural Fire Prot. Level 3 OCCUPANT LOAD: 701 TD = 185 EXITS DOORS EXITS STAIRS CORRIDORS ELEVATORS/LOBBIES BUSINESS ASSEMBLY STORAGE HAZARD TRAVEL DISTANCE At least 3 exits required: Occupant Load more than 500 but no more than 1000 Travel distance shall not exceed 300 ft. Business
Prescriptive Mean of Egress Structural Fire Prot. Level 4 OCCUPANT LOAD: 463 EXITS DOORS EXITS STAIRS CORRIDORS ELEVATORS/LOBBIES BUSINESS ASSEMBLY STORAGE HAZARD TRAVEL DISTANCE TD = 185 At least 2 exits required Occupant Load less than 500. Travel distance shall not exceed 300 ft. Business
Prescriptive Mean of Egress Structural Fire Prot. Level 5 OCCUPANT LOAD: 263 TD = 152 EXITS DOORS EXITS STAIRS CORRIDORS ELEVATORS/LOBBIES BUSINESS ASSEMBLY STORAGE HAZARD TRAVEL DISTANCE At least 2 exits required Occupant Load less than 500. Travel distance shall not exceed 300 ft. Business
Prescriptive Mean of Egress Structural Fire Prot. Level 6 OCCUPANT LOAD: 252 TD = 152 EXITS DOORS EXITS STAIRS CORRIDORS ELEVATORS/LOBBIES BUSINESS ASSEMBLY STORAGE HAZARD TRAVEL DISTANCE At least 2 exits required Occupant Load less than 500. Travel distance shall not exceed 300 ft. Business
Prescriptive Mean of Egress - Summary Summary: Number of Exits Level Occupant Load Number of Exits (Required by Codes) Number of Exits (Existing in CSM) Compliance Status 1 703 3 5. 2 523 3 7. 3 701 3 4. 4 463 2 4. 5 263 2 2. 6 252 2 2.
Prescriptive Mean of Egress - Summary
Prescriptive Fire Detection and Alarm Systems The building is a PROTECTED PREMISE. Signals sent to the University Police Department's Communications Center which is staffed 24 hours a day, 7 days (supervising station). Fire alarm system: Proprietary supervising station alarm system. Emergency communication system : One-way Fire Emergency Voice/Alarm Communications (EVACS). Two-way Emergency communication System (Telephone System).
Prescriptive Fire Detection and Alarm Systems System Type : Class B, Addressable and Manual Detection Performance of Notification Appliance Circuits (NACs). Performance Signaling Line Circuits (SLCs). Alm: Alarm. Trbl: Trouble. ARC: Alarm receipt capability during abnormal conditions. R: Required capabilities. X: Indication required at protected premises
Prescriptive Fire Detection and Alarm Systems FACU location in Room 122. Honeywell Notifier
Prescriptive Fire Detection and Alarm Systems The building IS NOT classified as a high-rise building and it is equipped throughout with an automatic sprinkler system: Requirements: Partial or Selective Coverage. Code (NFPA 72-5.5.2.2) A fire alarm system for occupancies with an atrium connecting more than two stories (CBC-2007-907.2.13) A fire-fighter's smoke control panel (CBC-2007-909.16) An two-way FD communication system (CBC-2007-907.2.12.3) Detectors : Detectors for Elevator Recall for Fire Fighters Service (NFPA 72-6.16.3.5) Detectors for Door Releasing Service (NFPA 72-5.16.6.5.1.1). Detectors for Automatic Shutoffs of Air-Moving systems (CMC -2007 609.0)
Prescriptive Fire Detection and Alarm Systems Automatic and manual detection devices Automatic smoke detectors: Spot type smoke detectors. Duct smoke detector. Beam smoke detectors Automatic supervisory signal devices: Sprinkler water flow device. Pump activation. Supervisory signal devices : Control valve tamper switch /Smoke Fire Damper position indicator. Manual devices: Manual fire alarm boxes (pull station).
Prescriptive Fire Detection and Alarm Systems Automatic and manual detection devices
Prescriptive Fire Detection and Alarm Systems Audible and visible notifications appliances Strobes. Speakers. Speaker/Strobe combination. Bells Annunciators
Prescriptive Fire Detection and Alarm Systems Audible and visible notifications appliances
Prescriptive Fire Detection and Alarm Systems OPERATION MATRIX
Prescriptive System Type: Fire Suppression System Wet Pipe System Design Criteria: Density/area method and the occupancy classification Light Hazard (Lobbies, Lecture, Office, and Conference Rooms) Ordinary Hazard Group 1 (Labs, Mechanical, Storage and Elect. Rooms) Water Supply: Fire Pump: Piping: Public Water Main 1 fire pump rated 113psi @ 750 gpm w/electric motor Black steel sch. 10 and sch. 40 Sprinklers installed in accordance with NFPA 13, 2007 (CBC 903.3.1.1)
Prescriptive Fire Suppression System Fire Hydrant Flow Test
Prescriptive Fire Suppression System Rated 113psi @ 750 gpm The sprinkler system is supplied by a public water main The fire pump feeds four (4) standpipe systems (one in each stair) and 6 sprinkler systems (6 risers, one for each floor). The system can also be supplied by a Fire Department Connection (FDC)
Prescriptive Fire Suppression System Design Criteria : Occupancy Classification: OCCUPANCY HAZARD Protection Area (Sprinkler - ft 2 ) DESIGN A-3 Lobbies/Lectures Light Hazard 225 0.10 gpm/ft 2 1500 ft 2 B Office/Conference Room Light Hazard 130 0.10 gpm/ft 2 1500 ft 2 B Laboratories O.H. GR. 1 130 0.15 gpm/ft 2 1500 ft 2 S-1 Storage/Mech./ Electric Room O.H. GR. 1 130 0.15 gpm/ft 2 1500 ft 2
Prescriptive Fire Suppression System Sprinklers Layout Level 1 Sprinklers were mainly recessed pendent sprinkler installed in Lecture, Conference, Office and Laboratory Room. Some upright sprinklers used in Mechanical rooms, Elevator Mach. Room, Electrical Room, Telecommunication/Data Room and Stairs, and Horizontal Sidewall Sprinklers were used in elevator wells
Prescriptive Fire Suppression System Sprinklers Layout Level 1 Designer Calculation: HydraCAD Hand Calculation 1-1
Prescriptive Fire Suppression System Sprinklers Calculations Level 1 (Area 1-1) Hand Calculation Area 1-1
Prescriptive Sprinklers Calculations Fire Suppression System The design criteria is reduced 39.25% for Remote Areas 3-1, 3-2, 6-2 & 6-3. The reduction is based on: Design area reduction for quick response sprinklers : No unprotected ceiling pockets, Ceiling heights of 10 6. Ordinary Hazard Group 1 (Laboratories) CBC 2007 Reduction is not permitted in CBC 2013
Prescriptive Fire Suppression System Sprinklers Calculations The design criterion is reduced 39.25% for Remote Areas 3-1, 3-2, 6-2 & 6-3.
Performance Based Performance Criteria Any occupant who is not intimate with ignition shall not be exposed to instantaneous or cumulative untenable conditions.(nfpa 101-2006 - 5.2.2) A Fire Barrier is not required between the atrium and the adjoining spaces of any three floors of the atrium, provided such spaces are accounted for in the design of the smoke control system (CBC-2007, Section 405.5, Exception 3)
Performance Based Performance Criteria Ref. SFPE, 2007 - Guide to PBD
Performance Based Performance Criteria ASET > RSET ASET Time from ignition until the building becomes untenable RSET Time to evacuate from the room/ space/ building Detection time (t d ) Notification time (t n ) Pre-movement time (t p-e ) Travel time (t e )
Performance Based RSET td (detection time) RSET = t d + t n + t p-e + t e t n (notification time) t p-e (pre-movement time) t e (travel time) Travel Time (t e ) Time when all occupants are evacuated out of Zone 1 (Atrium). - Hydraulic model of emergency egress (SFPE Handbook) - Compare with STEPS Computer Evacuation Model - PATHFINDER
Performance Based RSET RSET = t d + t n + t p-e + t e Parameter Time (s) t d + t n 30-60 Justification Open atrium, Primary detection: Building occupants seeing smoke rise through the atrium t p-e Reference: Proulx, SFPE Handbook, Table 3-13.1 60 Scenario W1: Live directives using a voice communication system from a control room with closed-circuit television facility, or live directives in conjunction with well-trained, uniformed staff that can be seen and heard by all occupants in the space. 180 Scenario W2: Nondirective voice messages (prerecorded) and/or informative warning visual display with trained staff.
Performance Based RSET RSET = t d + t n + t p-e + t e Level Occupant Load (# persons) Atrium Exit Area (ft 2 ) Density: D (persons/ft 2 ) Movement Speed (ft/min) m/s Travel Distance (ft) t e SFPE Handbook t e STEPS Computer Evacuation Model 2 77 3675 0.021 235 1.2 100 26 21 3 155 1835 0.084 209 1.06 117 34 37 4 64 4170 0.015 235 1.2 152 39 34 5 67 4227 0.016 235 1.2 152 39 40 6 68 4213 0.016 235 1.2 152 39 39
Performance Based RSET RSET = t d + t n + t p-e + t e Level Occupant Load (# persons) Atrium Exit Area (ft 2 ) Density: D (persons/ft 2 ) Movement Speed (ft/min) m/s Travel Distance (ft) t e SFPE Handbook t e STEPS Computer Evacuation Model 2 77 3675 0.021 235 1.2 100 26 21 3 155 1835 0.084 209 1.06 117 34 37 4 64 4170 0.015 235 1.2 152 39 34 5 67 4227 0.016 235 1.2 152 39 40 6 68 4213 0.016 235 1.2 152 39 39
Performance Based RSET - Pathfinder Travel Time : Age Demographics Age OCCUPANCY Percent (%) 20-30 Young 15 9 30-50 Middle 63 47 Doubled 50-61+ Old 16 32 All ages Disable 6 Doubled 12 * Reference: Assessment of Photo-luminescent Material during Office Evacuation, 1999, Table 5 and Smoke Management Study- Atrium Smoke Control, 2009
Performance Based RSET - Pathfinder Occupant Walking Speeds (m/s) Occupant Type Horizontal Down Stairs Up Stairs References Young 1.3 0.8 0.6 Fruin, 1987 and Fahy, 2001 Middle 1.2 0.7 0.5 Fruin, 1987 and Fahy, 2001 Old 1.0 0.6 0.4 Fruin, 1987 Disable 0.5 0.27 0.216 Fruin, 1987 and Boyce, Shields, and Silcock, 1999 Reference: Smoke Management Study- Atrium Smoke Control, 2009
Performance Based RSET - Pathfinder Occupant Load/level 2 3 4 5 6 77 155 54 67 68
Performance Based RSET - Pathfinder
Performance Based RSET - Pathfinder Level t e SFPE Handbook t e STEPS 2 26 21 3 3* 34 37 RSET = t d + t n + t p-e + t e t e PATHFINDER 6% Disabled Go to Any Exit Scenario A t e PATHFINDER 6% Disabled Go to Refuge A Scenario B t e PATHFINDER 12% Disabled Go to Any Exit Scenario C 38 24 38 104 104 104 16* 27* 24* 4 39 34 69 69 69 5 39 40 52 51 52 6 39 39 56 49 56 * The 1-hour fire rated walls are considered adequate to retain occupants within the student work spaces.
Performance Based RSET - Pathfinder Level 2 3 Detection and Notification Time (s) t d + t n RSET Pre-movement and Action Time (s) T p-e Travel Time (s) t e RSET (s) 1.5X RSET (s) = t d + t n + t p-e + t CBC Section 909.4. e 24 144-264 216-396 104 224-344 336-516 3* 27 147-267 221-401 60 60-180 4 69 189-309 284-464 5 51 172-291 257-437 6 49 169 289 254-434 * The 1-hour fire rated walls are considered adequate to retain occupants within the student work spaces.
Performance Based ASET - Tenability Criteria Design Criteria (Limits) Tenability Limit Source Temperature 140 F(60 C) NFPA 130, Standard for Fixed Guideway and Passenger Rail Systems Visibility 42 feet (13 meters) Jin, SFPE Handbook, Table 2-4.2. Radiant Flux Smoke Temperature 1.7 kw/m 2 350 F (180 C) SFPE Engineering Guide, Predicting 1 st and 2nd Degree Skin Burns from Thermal Radiation Carbon Monoxide 1,000 ppm for 30 min NFPA 101, Life Safety Code
Performance Based Design Fire Scenarios ASET - FDS Qualitative Hazard Analysis: o Potential ignition/fuel sources based upon representative materials and equipment within various areas. Heat Release Rate Curves: o Fire scenarios quantified by assuming a fast t² fire, based upon the types of hazards likely in the building. Maximum Heat Release Rate. o Based upon the expected time for sprinkler activation and the maximum fire size of a given fuel package. Determination of Smoke Production. o Soot yields corresponding to polyurethane foam with some cellulosic material (effective yield of 5%).
Performance Based ASET - FDS Design Fire Scenarios *Heskestad and Delichastios Correlations ** FDS fire size Scenario Location Fire Control HRR Curve *HRR max (kw) **HRR max (kw) DF#1 Level 2, atrium center Sprinkler-controlled Fast t² 1411 @ 174 s 1500 DF#2 Level 2, high-bay space Fuel-controlled Fast t² 2500 2500 FD#3 Level 4, student work space Sprinkler-controlled Fast t² 1250 @ 163 s 1300 DF#4 Level 5, atrium center Sprinkler-controlled Fast t² 1411 @ 174 s 1500
Performance Based ASET - FDS Current Project - Pathfinder Smoke Management Study, 2009 Level RSET (s) ASET (s) Results 2 216-396 1200 OK - OK 3 336-516 240 FAIL - FAIL 3* 221-401 240 OK - FAIL 4 284-464 400 OK - FAIL 5 257-437 320 OK - FAIL 6 254-434 180(240) FAIL - FAIL Level RSET (s) ASET (s) Results 2 212 1200 OK 3 236 240 DF#1 OK - - - - 4 231 400 DF#2 OK 5 240 320 DF#3 OK 6 239 180(240) DF#4 FAIL (OK) *Level 3 excludes the student work spaces from evacuating because a 1- hour fire rated wall separates the atrium space from all other areas on this Level. The RSET calculations were performed with the software PATHFINDER considering pre-movement times of 60 and 180 seconds (W1 and W2).
Performance Based ASET - FDS Smoke Management Study Assumptions: HRR
Performance Based ASET - FDS Smoke Management Study Assumptions: HRR
Performance Based ASET - FDS Smoke Management Study Assumptions: Visibility C = 8 Light-emitting Sign (5 to 10) 13 m 13 m 13 m C = 3 Light-reflecting Sign (2 to 4) 7 m 5.3 m 6.7m
Performance Based ASET - FDS Smoke Management Study Assumptions: Visibility C = 3
Performance Based ASET Smoke Control System Exhaust Method NFPA 92 Design Fire : 3,120 kw Smoke Rate Production m = 156 kg/s Makeup Air Requirements (90 %) V = 117 m 3 /s. Supply vents A = 115 m 2 v < 1.02 m/s Maximum volumetric flow rate - plug-holing V max = 16.6 m 3 /s. Volumetric flow rate of smoke exhaust V = 133 m 3 /s Number of exhaust vents N Vents = 7.9 8 exhaust vents A = 126 m 2
Performance Based ASET Smoke Control System Exhaust Method Design fires - Mechanical Smoke Control System Most severe cases Design Fire A (DFES-A): DF#2 HRR - 2,500 kw - Produces the most smoke and requires the highest exhaust rate. Design Fire B (DFES-B): DF#2 HRR - 3,120 kw - Produces the most smoke in the first stages of the fire. Design Fire D (DFES-C): DF#4 HRR - 1,500 kw - It makes fail the tenability criteria on Level 6 at 180 seconds, which is the worst ASET obtained in the study.
Performance Based ASET - RSET Smoke Control System Exhaust Method Design Fire D (DFES-C): DF#4 HRR - 1,500 kw Design Fire A (DFES-A): DF#2 HRR - 2,500 kw
Performance Based Conclusions - The CSM complies with the prescriptive requirements stated on the applicable codes. - The performance-based analysis, however, showed that different results might be obtained depending on the assumptions made for the evaluations. When the RSET STEPS, and t p-e is assumed to be 60 seconds, the ASET is greater than the RSET for all levels. When the RSET PATHFINDER, different results obtained depending on the t p-e assumed (60/180), and only Level 2 passed the tenability criteria regardless the t p-e considered.
Performance Based Conclusions - The Smoke Management Study assumed t p-e = 60 s on the basis that DF simulated are in relatively close proximity to the observe smoke and flames. occupied spaces, so the occupants would clearly be able to - The validity of this assumption may be challenged since: There are administrative offices and work spaces that subdivide the atrium space on Levels 2-6. The EVAC system installed operates through pre-recorded voice messages (W2) t p-e =180 s. - The simulation of the atrium with a Mechanical Smoke Control Systems showed that all levels in the atriums successfully pass the tenability criteria evaluated, regardless the pre-movement time considered.
Performance Based Recommendations - Prepare and implement a Fire Safety Management Plan for the building, in conformity with the requirements of the IFC, Chapter 4, including: The location of furniture to be allowed in the atrium at its different levels. The procedures and requirements for a staged evacuation in the building, which allow occupants within close proximity of the fire to evacuate the building first. - Conduct a detailed study in the current conditions of the building, in order to ascertain more accurately the validity of the assumptions made in the previous Smoke Management Study.
Performance Based Recommendations - Make the decision of redesign or change the EVAC system currently operating through pre-recorded voice messages, for a W1 system (60 s). - Conduct a detailed cost-benefit analysis for determining the feasibility of: Installing a mechanical smoke control system in the atrium Improving/changing the current natural smoke controls systems - The analysis should revolve on conservative assumptions in order to rely on a system able to provide 1.5 times the RSET for the safe occupant evacuation
Performance Based Acknowledgments - My sincere gratitude to all in the Cal Poly s FPE program, in particular to Frederick W. Mowrer and Christopher C. Pascual for their support during the whole period of study. - I would also like to acknowledge the following persons/companies for providing documentation/information as well as support to this project: Kevin Fagan, CAL POLY, SLO. Rex Wolf, CAL POLY, SLO. Curtis Streeter, DEEP BLUE INTEGRATION, INC. Stacey Williams, ZGF ARCHITECTS LLP Brian McLaughlin, ARUP Antonio Campo, UTSA
Culminating Project Fire Protection and Life Safety Engineering Analysis Thank you Center for Science and Mathematics Cal Poly Questions? Orelvis Gonzalez March 20 th, 2015