Comprehensive maintainability scoring system (COMASS) for commercial buidings in tropical climate of singapore 2

Chapter Defect Analysis 4.1 Introduction This chapter presents the results of the field investigation and questionnaire survey, as well as provides answer for the first research question: “What are the key factors that affect maintainability and how they influence?” The answer fulfils the first research objective to improve the knowledge-base of building systems, associated defects and their analysis in terms of causes and effects It has already been realized that maintainability essentially means mitigation of defects Hence analysis of the causes and criticality of effects of common building defects can provide a suitable answer Proposed ‘Defect Library’ or DL is a comprehensive central database that contains a brief literature review on defects associated with various building subsystems, analysis of causes and criticality of effects Critical defects are short listed from the entire list Influence of defects on maintainability was first documented during 2002-2004 for facade and wet area (Chew, 2004) In this research those two sections were also dealt along with other seven subsystems The final output of DL was made available online at the research website (www.hpbc.bdg.nus.edu.sg) 4.2 4.2.1 General findings of questionnaire survey Demographic information Through 27 individual owners, developers and 22 facility management companies, a total of 89 contacts were made ((31% owner, 20% developer and rest FM company) - cases by each of last two groups as they have different types of commercial buildings under their supervision Though for questionnaire and discussion total 40 positive replies were received, 34 were finally completed and for case studies FMs of only 14 buildings agreed The sample size of 34 fulfilled the requirement of minimum sample size for a statistically sound analysis (Tan, 2004) Table 4.1 and Fig 4.1 show demography of the case study buildings and the 68 professionals who provided valid responses respectively The buildings investigated were 335 years old, 3-66 storey high, scattered all over the island and had all possible types of commercial usages Slightly higher (57%) responses were received from FMs who maintain their own buildings Probably for the other group, obtaining client’s permission to reveal building defects was difficult However for questionnaire survey and interviews, instead of building related specific data, generic perception of defects was asked and the response rate was almost equal – 46% from developer/ owner company and rest from FM company Out of 34 respondents, majority (55 %) have 5-10 years of experience, 24% are new in the industry (< 5years), 12% have 10-15% years and 6% of 15-20 years of experience and while rest 3% have a very long experience In fact out of this last two groups, one has been involved in conceptualization of new projects of his company and another person played a key role in the renovation of his building Table 4.1 Details of case study buildings Sr Main usage no Shopping mall Shopping mall Shopping + community ctr Office Office Office Office Office (govt.) Office (govt.) 10 Office + retail 11 Business park 12 Business park 13 Hotel 14 Hotel + entertainment Note: GFA = Gross floor area GFA Age Main(sq m) (yrs) tained by Industrial 35000 17 Self Commercial 52800 31 Self Residential 20000 10 Self Mixed 42 83160 22 Self Mixed 24 21300 Self Mixed 18 17200 12 Self Commercial 30 27000 FMC Residential 24 42650 FMC Commercial 25 106420 FMC Commercial 66 88650 13 Self Mixed 11 110000 14 Self Industrial 66500 18 FMC Commercial 36 45900 35 FMC Commercial 96600 FMC FMC = Facility management company Location FM Company, 15, 44% Fl No 5-10 years, 19, 55% Ow ner, 12, 35% Developer, 7, 21% Work profile 20 years, 1, 3% Years of experience Fig 4.1 Demography of the respondents 69 4.2.2 Significance of grading criteria and building subsystems Respondents graded both parameters of defect criticality and subsystems in a 5-point scale Though they had the freedom to add subsystems if necessary, but no new element was suggested Key findings from statistical test (Appendix B.1) are shown in Table 4.2 The t-test of the means indicated that all the subsystems were considered important for maintainability of commercial buildings Kruskal-Wallis one-way ANOVA revealed that there was no significant difference between the opinions of respondents from the developer, owner and FM company Henceforth, for defect grading, no discriminations were made among the groups Table 4.2 Significance of grading criteria and building subsystems Elements tested Criticality parameters Freq of occurrence Impact on economy Impact on sys perf Impact on health, safety One sample t-test results Mean SD t p 3.74 3.65 3.97 3.91 0.86 0.73 0.67 0.75 4.96 5.14 8.40 7.06 0.000 0.000 0.000 0.000 Gr1 19.08 14.54 22.33 19.71 Building subsystems Basement 3.76 0.99 4.52 0.000 18.75 Facade 4.18 0.83 8.23 0.000 15.00 Wet area 4.03 0.90 6.64 0.000 16.46 Roof 3.94 0.98 5.58 0.000 16.62 Sanitary-plumbing 3.82 1.03 4.67 0.000 19.17 HVAC 4.44 0.66 12.73 0.000 15.12 Elevator 4.32 0.68 11.28 0.000 19.96 Electrical 4.06 0.95 6.49 0.000 15.75 Fire protection 3.79 0.98 4.74 0.000 21.79 Note: df for t-test is 33 and for Kruskal-Wallis test is Gr1= individual building owner’s FM Gr2= developer’s FM 4.2.3 Mean rank Gr2 Gr3 15.00 17.29 16.07 13.21 17.40 19.97 14.30 17.73 KW stat p 0.86 2.39 5.62 2.18 0.652 0.302 0.060 0.336 18.21 16.17 0.57 0.751 20.36 18.17 1.61 0.447 17.86 18.17 0.23 0.890 18.29 17.83 0.17 0.918 15.00 17.33 0.85 0.654 18.86 18.77 1.33 0.515 14.93 16.73 1.56 0.459 22.07 16.77 2.16 0.340 11.29 16.97 5.48 0.065 Cut-off t-value =1.6931 Gr3= FM company employee Format of defect reporting These generic rules are applicable to all nine subsystems As per FMECA concept, each subsystem was divided into as many components as possible Defects pertaining to particular subsystems were grouped under relevant components and coded Photographs of visible defects were also grouped in the same manner Basement defects were coded as A1, A2, ,An Similarly defects were coded for other subsystems namely, facade (B1, B2, , Bn); wet area (C1, C2, , Cn); roof (D1, D2, , Dn); sanitary-plumbing (E1, E2, ,En); HVAC (F1, F2, ,Fn); elevator (G1, G2, ,Gn); electrical (H1, H2, Hn); and fire protection (J1, J2, ,Jn) There was no defect code ‘I’ to avoid confusion with numeric ’1’ 70 Causes of each defect were grouped under four categories, namely, design / specification (D); construction / installation (C); maintenance (M) and external factors (E) Criticality analysis of defects includes: (1) statistical t-test on ratings for four criticality parameters to identify the critical defects and (2) determination of criticality index Cr The key findings are explained in details in the following sections Detailed SPSS output of t-test for nine subsystems are presented in Section 2- 10 of Appendix B 4.3 Defects in basement A basement is that part of a building structure that is below ground level and therefore subjected to external hydrostatic pressure Due to their exposure to surrounding soil conditions, basements tend to suffer from a faster rate of deterioration than any other building elements, (Sandeford, 1995) Leakage of water through cracks or vapour transmission through porous surface can cause damage to the structure and make the place inhabitable Residual soils in Singapore are product of tropical weathering and covers 2/3rd of the area Generally formed above the groundwater table, this soil is usually unsaturated Water carrying contaminants can move over a longer distance along soil strata before reaching the ground water table (Rezaur et al, 2002) As Singapore soils include both their saturated and unsaturated properties (Augus, Leong & Rahardjo, 2001), such unpredictable environment leads to premature deterioration of the under ground structure Defects mainly due to water seepage are common and tedious problem in Singapore (Chew & Egodage, 2003) Basements are designed, constructed and maintained to keep them free from moisture and dampness Durability is vital for a basement structure as there is limited scope for maintenance and repair (Henshell & Griffin, 1999) From a survey of 61 buildings in Singapore, 987 cases of water seepage and other prevalent defects were identified by building maintainability research team (Chan, 2005; Hing, 2003; Ho, 2003) The major components of basement are: structural members, waterproofing system, finishes and services From field 71 studies and a thorough literature review, the prevalent defects pertaining to basements are documented in Fig 4.2 and Table 4.3 followed by analysis of causes and criticality Structural elements Corrosion & spalling Seepage through joint Efflorescence at joints Seepage through cracks Seepage thru’ porous concrete Finishes on floor wall and ceiling Flaking & peeling Blistering Crazing Rust stain Tile cracking Damp / dirt stain Dirt / oil stain on floor Stains on false ceiling Biological growth Others Water ponding Water seepage through service penetration Fig 4.2 Common defects in basement 72 Table 4.3 Common defects in basement and their causes Defects & coding Water leakage through joints (A1) Efflorescence at joints (A2) Water leakage through concrete (A3) Seepage though cracks Usually with rust staining and may lead to efflorescence (A4) Corrosion & spalling of concrete (A5) Damp patches (A6) Blistering (A7) Paint peeling & flaking (A8) Paint crazing (A9) Damp and dirt patch (A10) Rust stain (A11) Tile cracking (A12) Possible causes of defects Structural elements Poor design detailing E.g congestion of rebar Discontinuity at joints or poorly finished joints Insufficient curing and vibration Improper installation of water proofing or waterstops Wrongly selected or bent waterstops unable to provide protection Aging of water proofing membrane or waterstops Leaching of soluble salt or un-hydrated lime from cement Poor quality control for cement and improper curing Delayed repair of leakage and irregular cleaning Inappropriate waterproofing technique & unsuitable material Deterioration of waterproofing with time or due to exposure to aggressive condition which is not considered in design Concrete is porous due to poor mix design or bad workmanship Wrong location, installation of waterproofing or its damage during by other trades Delayed repair of initial cracks, allows moisture to reach rebars The corrosion product has higher volume and causes spalling Concrete is exposed to water if the waterproofing is not properly installed or damaged with time Poor lay out of rebars that hinders vibration or poor compaction around rebars that leave concrete porous at certain places Plastic settlement cracks if water cement ratio is excessive or poor grading of aggregate Plastic shrinkage cracks if inadequate curing is done especially in warm and windy weather Insufficient vibration and pouring leaves voids and honeycombs Concrete is attacked by aggressive chemicals in soil No use of corrosion resistant bars, corrosion inhibitor in such special cases Delayed repair of initial cracks Inner cavity wall Material has high water absorption and low water resistance Rising damp if cavity is not designed or constructed properly to drain out the water Clogged and overflowing cavity Moisture bridging by debris Finishes Paint applied on wet (> 6% of moisture content) and warm surface traps moisture underneath the paint causing blistering This problem is especially prominent in poorly ventilated basements Unsuitable selection or poor quality of paint A breathable system that allows excess moisture to evaporate is preferable Poor surface preparation for substrate Dirt or other contaminants reduce adhesion between the surfaces Failed water proofing membrane allows water seepage that push off the paint film Paint is applied on wall suffering from shrinkage cracks Contaminated substrate, tools, water /thinner Fatty acid of alkyd based paint and alkali of concrete causes saponification or damp patches of soluble soap Leaching from corroded fittings or rebars Differential settlement of basement or shrinkage cracks of basement No proper movement joint provided to mitigate these Tiling on a cracked or uneven wall Cause gr D C M E ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ 73 Defects & coding Dirt & stains on tiles (A13) Tile debonding A14) Dark, damp patches on ceiling (A15) Dirt and oil stains on floor (A16) Efflorescence on floor (A17) Biological (algae, fungi) staining on surface (A18) Water leakage at service penetration (A19) Water ponding (A20) 4.3.1 Possible causes of defects Use of incompatible or poor quality grout No cleaning of tile surface after laying or dirt from other works Irregular cleaning Back of tile contaminated with dirt or dust No key provided Inadequate curing of substrate before tiling or porous tiles if not soaked properly, absorb water from substrate Tiles not properly tapped in position Water seepage from upper floor (usually below planter / pool ) Condensation and water seepage from HVAC ducts damage false ceiling boards Dirt and oil stains from vehicles remains unattended due to inadequate cleaning Oily patches due to saponification from paints Carbonation from CO2 form vehicles is confined in one place (usually for reserved parking) Trapped moisture if finishing coat is applied on damp substrate or water seepage from ground Excess seepage through deep / wide crack Concrete is porous or weak at poorly prepared construction joints Leaching of soluble salts or unhydrated lime from cement Poor quality control for cement and improper curing Delayed repair of leakage and irregular cleaning Poor ventilation and natural lighting Lack of inspection and cleaning Delayed repair of leakage Others Poor detailing and installation of water proofing around the pipe E.g no angle fillets at sharp turn, improper lapping etc Irregular inspection of leaky pipes Unplanned service penetration such as hacking can damage the structural element as well as the waterproofing Entry of surface water run-off No catchments provided Poor drainage design (insufficient slope / outlet) and Poor cleaning for water brought in by cars Uneven / dented surface due to poor levelling of floors Clogged internal drainage Uneven ground settlement due to massive change in ground water table or poor compacting of compressible soil Cause gr D C M E ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ Criticality analysis of defects in basement Out of 20 defects were found critical according to one or more grading parameters The results are shown in Table 4.4 Statistical tests and detailed calculation of Cr can be found in Section B.2 It was observed that most of the critical defects are related to water seepage through cracks, joints, penetration or concrete itself This observation is in agreement with earlier findings by Chew & Egodage (2003) Blistering on paints and dirt on floor are 74 common issues as mostly basements are used for service areas and parking Leakage through joints, concrete, cracks or service penetration was found critical as they affect the water tightness of basements Water ponding on floor is usually regarded as a nuisance and people prefer to avoid such parking options Hence the economic performance suffers Table 4.4 Criticality analysis of defects in basement Code Defects in basement ⎯XFR ⎯XEC Structural elements ▲ A1 Leakage at joints 2.79 2.82 A2 Efflorescence at joints 3.82 1.47 ▲ A3 Water leakage through concrete 2.21 3.76* ▲ A4 Seepage through cracks & rust stain 3.09 3.47* ▲ A5 Corrosion & spalling of concrete 1.62 3.24* Inner cavity wall A6 Damp patches 2.47 1.62 Finishes ▲ A7 Blistering 3.48* 1.41 A8 Paint peeling & flaking 3.09 1.47 A9 Paint crazing 3.79 1.88 A10 Damp & dirt patch 3.62 1.94 A11 Rust stain 2.56 1.61 A12 Tile cracking 2.44 1.06 A13 Dirt & stains on tiles 2.68 1.68 A14 Tile debonding 2.00 1.38 A15 Dark, damp patches on ceiling 4.12 1.79 ▲ A16 Dirt and oil stains on floor 3.62* 2.56 A17 Efflorescence on floor 2.44 1.29 A18 Bio-growth on surface 3.12 2.03 Services ▲ A19 Seepage at service penetration 2.62 3.53 ▲ A20 Water ponding 2.53 3.62* Note: * Represents the t-value that is higher than critical t-value (1.6931) ▲ Represents critical defects 4.4 ⎯XSP ⎯XHS Sv Cr 3.97* 3.03 4.32* 3.82* 4.18* 2.71 2.56 2.88 2.53 3.91* 3.17 2.35 3.66 3.27 3.77 0.354 0.360 0.323 0.404 0.244 1.94 1.50 1.69 0.167 2.82 2.18 1.35 1.50 1.74 1.32 1.29 1.88 2.12 2.21 1.24 1.65 1.47 1.26 1.18 1.47 1.26 1.32 2.24 2.79 1.65 1.18 1.35 3.21 1.90 1.64 1.47 1.64 1.54 1.24 1.74 2.02 1.85 1.98 1.29 2.29 0.265 0.202 0.223 0.237 0.157 0.121 0.186 0.162 0.305 0.287 0.126 0.286 3.71* 3.35* 3.12 3.32* 3.45 3.43 0.361 0.347 Defects in facade Fig.4.3 and Table 4.5 present the common facade defects identified in this study A comprehensive defect list for various types of building facades has been reported by Chew, De Silva & Tan (2004) They reviewed 120 buildings of both traditional and modern facade and found various defects in prevalence, to name a few, cracking, rising dampness, tile debonding, biological growth, sealant failure, efflorescence etc Many of these defects arise from poor accessibility for inspection and cleaning especially for iconic buildings with uncommon shape (Briffet, 1995) Staining may also arise from water run-off controlled by protruding or decorative elements (Chew & Tan, 2003) 75 Exposed brick masonry Cracking Staining Rising dampness Biological growth Concrete masonry wall Cracks & spalling Unevenness & spalling Efflorescence Sealant deterioration Glass facade Biological attack Sealant failure & stain Cracks & shattering Surface cracks Delamination Biological growth Dirt stains Efflorescence Crazing Discolouration Plastered wall Painted wall Alligorating Blistering and peeling Chalking Biological growth Yellowing Staining & dirt streaks Fig 4.3 Common defects in facade 76 Tile cladding Cracking Tile delamination Efflorescence Biological growth Staining Tile chipping Efflorescence: salt stain, patch Rising dampness Natural stone cladding Staining: rust, chemical or dirt stain Biological growth : fungal or algal growth Cracking of surface Uneven surface Metal cladding Dirt stain: mark/ discolouration Colour inconsistency or ‘chequered effect’ Deformation-buckling, warping, deflection Coating discolouration or colour change Cracking Fixing failure Scratches & abrasion Joint failure Misalignment of joint Sealant failure Fig 4.3 Common defects in facade(Continued) 77 Transformer Transformer on fire Room used as storage Damp stuffy room Worn protective mat Corroded metal conduit Exposed raceway Cable & wiring Worn insulation Burnt cable RG: ε : SC: NORM 07/04/30 12:44:52 (120.0) 55 55 53 53 51 51 49 49 47 47 45 45 43 43 41 41 39 39 (-40.0) Corroded busbar trunking Hot connector (thermal image) Lighting Control gear RG: ε : SC: NORM Exposed wire & loose connection 07/04/30 12:06:28 (120.0) 53 51 49 47 45 43 41 39 37 (-40.0) Over heated CB (thermal image) Corroded CB Decolorized casing outdoor light of Burnt ballast of blown lamp Seepage in elec closet Overloaded plug point Burnt receptacle Unsecured clamp/joint Exposed grounding rod Accessories Blocked switchboard Earthing & lightning protection Corroded conductor Galvanic corrosion Fig 4.10 Common defects in electrical system 117 Table 4.17 Common defects in electrical system and their causes Defects & Coding Short circuit (H1) Poor performance of equipment (H2) Nuisance tripping (H3) Shock & electrocution (H4) Arc, spark (H5) Difficult identification / rectification of defect (H6) Total power cut from one fault (H7) Possible causes of defects General performance & hazards Poor design details of busbars or cables in terms of centre line spacing, size, strength and provision of mechanical supports No / faulty protective device Poor insulation or inadequate conductor spacing causes impedance Current supplied at lower than rated is example of poor planning or wrong tap adjustment of transformer Voltage-drop during starting of big motors causes momentary poor performance Supply is of under capacity or not divided into sections Voltage-drop in undersized conductors Wrong wiring connection at receptacles causes different voltage Rating mismatch of equipment and supply Supply is far away from load centre of building and hence overloading at one part of the building occurs Fuse of wrong rating or non-calibrated circuit breaker (CB) –usually from careless maintenance (Love, 2001) Transformer tap setting at lower standard may hike load Loose connections causing spark, overheating or burning Single phase circuit catering three phase equipment Under-capacity of circuit to cater appliances with higher load factor Wrong polarity (e.g switch gear connected to neutral) This may give shock even when the equipment is switched off Deterioration of protective coverings / insulation with time or carbonization due to high voltage difference across insulation Condensation on exposed live part This happens if other services cross through electrical room or closet Improper grounding or ‘mis-wiring’ Faulty/ no GFCI Accidentally if any metal tool or ladder bridges the gap between two conductors, current flows through an unintended part of the circuit No/ poor connectivity of grounding system to clear the fault (H38) Damaged / charred insulation by careless splicing, mechanical impact, use of wrong cleaning chemical, exposure to high sources or aging Bridging two exposed conductors by metallic tool Places under regular O&M should not have exposed cabling Connectors are loose or have inadequate tip pressure, non removal of oxide, rusting etc Very high resistance at connections if conductors are clamped together without sufficient contact pressure, corrosion of contactor or use of dissimilar material with different thermal expansion Mechanical failure (creep) with time Water enters through poorly detailed / finished transition points and corrodes conductor Short circuit heating in undersized conductor Haphazard wiring and wrong colour coding Cramped wires in undersized junction box or outlet box also results in haphazard wiring No ‘as built’ drawing available esp for changes made by tenants Distribution boards (DB) should also be preferably labelled Inadequate number of intermediate pull or junction box Difficult pulling over sharp bends in conduit Long distance between junction boxes makes it difficult to replace any damaged wire Wrong / no provision of circuit breaker at desired isolation Ballasts if not fitted with in-line fuse-holder and time delay fuse, one failed unit causes black-out in entire area Defect gr D C M E ▲▲ ▲ ▲ ▲▲ ▲▲▲ ▲ ▲ ▲ ▲▲ ▲ ▲ ▲▲▲ ▲▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲▲▲ ▲▲▲▲ ▲ ▲▲ ▲▲ ▲ ▲▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲ 118 Defects & Coding Vibration and noise (H8) Overheated or burnt body, feeder etc (H9) Oil leakage (H10) Damaged insulation (H11) Unsuitable / unsafe working condition (H12) Overheated / burnt (H13) Mechanical damage (H14) Corroded metal parts (H15) Damaged insulation (H16) Possible causes of defects Transformer Overloading and fluctuation density of core Loose connection of bolt on clamping structure Use of wrong sized crimp or improper tool No precaution of sound isolating pad / vibration damper for mounting Insufficient air ventilation in the room for heat dissipation Loose or wrong sized parts increase resistance Over greasing, lack of proper tool & training cause loose connections Eddy current, excessive overloading No thorough investigation to detect the problem in inner parts Dirt or grime from insulation and windings prevent heat dissipation Foreign make - not suitable for higher ambient temperature of tropics Careless lubrication Excessive corrosion overlooked for a very long time Damage during transportation is not checked before installation Poor cleaning – often hindered by poor access High acidity of cooling liquid Should be checked and changed Breakdown of insulation from overheating (H9) Insufficient space design or transformer room is used as storage Protection mat deteriorated with time or spillage of chemicals Inadequate lighting and ventilation Slippery and dirty floor surface from oil spillage or scattered parts Omission or missing warning sign or locks Door mechanism of transformer room is not set to de-energize transformers upon opening the door Cable and wiring Narrow cross section or excessive length causes resistance heating Exposed to direct sunlight or other heat sources Short circuit or ground fault Overloaded busbar K-rated transformer can reduce harmonics Movement or dangling if support is not secured or insufficient Broken / loose supports from excessive corrosion Excessive tension – careless workmanship Too close to structural frame or no hangers to allow movement Damage is more prominent in absence of expansion joint or open run Inadequate protection from crushing, impact or abrasion Sharp or too many bends, pulled over excessive length Intermediate junction / pull box can solve such problem to a great extent Nicks during careless cutting results in broken wire beneath the cover Damaged during maintenance of other services running too close / interfering (Result of poor planning) Conductor not firmly secured – pulsating current causes sway Missing cover of junction/ pull box (H17) encourages vandalism Esp if the cables can be pulled easily due to gap between cable and knockouts Water seepage due to poorly designed / finished joint Use of unsuitable lubricant, pulling or cleaning agent Lashing water jet for cleaning enters through ends or joints which are not properly designed or sealed Adjacent structure is not water resistant Galvanic corrosion Softened from prolonged exposure to high temperature (>70°C) Use of unsuitable lubricant, pulling or cleaning agent Narrow cross section or excessive length causes resistance & heating High inrush current from short circuit (H1) or ground fault Defect gr D C M E ▲ ▲ ▲ ▲▲ ▲▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲▲ ▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲▲ ▲ ▲▲ ▲ ▲ ▲ ▲▲ ▲ ▲ ▲ ▲▲ ▲▲▲▲ ▲▲ ▲▲ ▲▲ ▲ ▲ ▲ ▲▲ ▲ ▲▲▲ 119 Defects & Coding Damaged elec box (H17) Unsafe switchboard or panelboard (H18) Burnt mark or smell in switchboard or panelboard: (H19) Outlet box unsafe (H20) Noise / spark (H21) No power at receptacle(H22) Jam/ loose switchgear / switch (H23) Inaccurate meter (H24) Frozen / unable to trip (H25) Noisy contactor (H26) Lamps blink, flicker, freq blow off (H27) Less light (H28) Defect gr D C M E Intermediate (junction or pull) box – not made of rust proof material ▲ Knockouts are made using improper tools or methods Should be ▲ done before mounting Knockouts are made forcefully big to accommodate too many cables ▲ Screw / cover missing during careless installation or maintenance ▲▲ Distribution equipment Insufficient space or inadequate access for proper operation and ▲ ▲ maintenance Warning notice / label – not provided, peeled off or not visible ▲ ▲ Insulation is damaged (crack, blister, warping) by overheating, ▲ ▲ physical impact or from spillage of cleaning chemicals Moisture ingress in the metal closet or it is unsuitable for exposure ▲ condition Shock hazard (H4) ▲▲ ▲ Rust, dirt causing high resistance and heating at cable contacts ▲ ▲ Burnt or charred insulation by exposure to external heat source or ▲ ▲ constant arc produced inside Inner components should be checked with special means Catering to too many protection devices or connections ▲ Adapter catering to too many devices - poor planning to ▲ accommodate future extension Poor design or furniture layout, stacking makes it inaccessible ▲ ▲ Resonant to the magnetic field generated by higher-frequency ▲ harmonic current Use of k-rated transformer is one of the solutions Internal contacts burnt or worn out from constant sparking ▲ Careless usage, e.g forceful insertion of flat pins in round slots ▲ Rough use or vandalism (esp switches in outlet box) ▲ Irregular cleaning and lubrication ▲ May require replacement after certain time ▲ Corrosion from poor make or water seepage in electrical closet ▲ Faulty device needs resetting ▲ Broken wires, dirt or dust impeding the movement ▲ Protective device Damaged by dirt, corrosion or mishandling ▲▲ Contacts are burnt if they are loosely fitted ▲ Improper design rating or wrong installation – should be tested ▲▲ Fuse of wrong rating or non-calibrated CB –usually from careless ▲ maintenance (Love, 2001) GFCI-deformed or missing pins, damaged insulation, incorrect wiring ▲▲ Interlock is worn with time or key is missing for mechanical type As ▲▲ a result CBs can’t function properly Poor contact in control circuit ▲▲ Low voltage causes chatter – rating mismatch with supply ▲ Lighting Voltage dip if cable between lamp and fused splitter is too long or a ▲ heavy motor without reduced voltage starter is in same supply line Exhausted lamp life Replacement needed ▲ No over current protection device (fuse / circuit breaker) provided ▲ Shadow casting by over-decorative luminaire ▲ Lumen output of lamps is inadequate ▲ Luminaire spacing is too high Usually such mismatch occurs when ▲ the luminaire can not be shifted according to new interior layout Covered by dirt, dust, and grime Poor maintenance or design of ▲ ▲ luminaire is prone to collect dust Reduced lamp life with time – no regular replacement ▲ Possible causes of defects 120 Defects & Coding No light (H29) Damaged casing (H30) Overheated / burnt ballast (H31) Noisy ballast (H32) Generator: noise, vibe & overheating (H33) Dirty, leaky generator body (H34) Damaged insulation (H35) No / delayed/ less power supply (H36) Corroded parts (H37) No /poor conductivity (H38) Damaged electrode (H39) Possible causes of defects Connection of lamp and corresponding switch is not proper Lights controlled by 2, or way switch mainly suffer from such coordination issues Blown lamp is not replaced Metal halide lamps upon voltage drop take few minutes to restart Wear and tear with time Exposure to direct weather condition Flickering lamps (H27) One of the paired lamps is removed or blown If it is not replaced for a long time, ballasts get overheated from spark Loose fitting in the ballast causes vibration Vibrations get amplified by large radiating surface of luminaires Good quality products are tested to pass such design defects Standby / emergency power supply Insufficient ventilation by radiator - water level is low or it has inadequate opening in the generator room Overloading or unbalanced load No acoustical control is provided Vibration isolator is ineffective due to improper mounting Vee belt is loose or too tight Filters are clogged and dirty Poor servicing – rusts should be removed and after that, parts should be painted or lubricated Damaged during transportation and not checked before installation Frequent / extended operation at stand by rating Overheating is not detected through testing for a long time Power source is not reliable or under capacity Wrong circuit design or wiring – it is unable to activate the generator or battery when the normal power supply is cut Such control should be tested and marking on DBs are recommended to avoid ambiguity Generator fails to start automatically due to insufficient air intake for combustion, excessive corrosion or faulty limit switch Battery goes flat – over discharged or not charged properly, tampered, electrolyte condition not satisfactory Leakage in battery due to excessive rusting, poor cleaning or painting Poor contact at any junction or battery terminals – careless maintenance or rusting esp in damp and dirty storage place Voltage-dip during transfer of power to alternate source if the transfer mechanism is faulty UPS should be used for critical circuits Grounding & lightning protection system (LPS) Dissimilar metals are connected without special precaution As a result Galvanic corrosion takes place Protective coating is damaged Should be checked regularly Earth electrodes / conductors are not resistant to weathering or deteriorate over a long period of time Inadequate contact with surrounding soil Incomplete network formed for all conductors in the building Surrounding soil has poor conductivity and not treated for the same Inadequate burial depth or improper driving damage conductors Fasteners are not corrosion resistant They become rusted and loosen contact over time Should be checked regularly Vandalism if cover of earth pit / inspecting chamber is not secured Thorough tests not conducted after installation and at specified interval to detect such faults Inadequate burial depth or careless excavation in vicinity Vandalism if cover of earth pit / inspecting chamber not secured Defect gr D C M E ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲ ▲▲▲ ▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲▲ ▲▲ ▲ ▲ 121 4.10.1 Criticality analysis of defects in electrical system In electrical system though 56% of defects are critical, only (10%) are frequent, namely, arc /spark and unsafe outlet box But 55% of those defects are related to safety (Table 4.17) Table 4.18 Criticality analysis of defects in electrical system Code Defects in basement Cr ⎯XFR ⎯XEC ⎯XSP ⎯XHS Sv General performance & hazards ▲ H1 Short circuit 1.82 3.29* 4.03* 3.71* 3.68 0.268 ▲ H2 Poor performance of equipment 2.41 3.26* 2.71 1.44 2.47 0.238 ▲ H3 Nuisance tripping 1.74 3.32* 3.44* 3.00 3.25 0.226 ▲ H4 Shock & electrocution 1.71 2.97 1.71 4.56* 3.08 0.210 ▲ H5 Arc, spark 3.44* 1.88 3.03 2.71 2.54 0.350 H6 Difficult identification / rectification of defect 1.74 2.41 2.62 1.97 2.33 0.162 H7 Total power cut from one fault 1.56 2.76 3.24 2.06 2.69 0.167 Transformer H8 Vibration and noise 1.62 2.24 2.44 2.71 2.46 0.159 ▲ H9 Overheated or burnt body, feeder etc 1.65 2.29 3.53* 3.00 2.94 0.194 ▲ H10 Oil leakage 1.26 2.44 2.85 3.29* 2.86 0.145 ▲ H11 Damaged insulation 1.38 2.18 3.76* 3.56* 3.17 0.175 ▲ H12 Unsuitable / unsafe working condition 2.03 2.59 2.53 3.47* 2.86 0.232 ▲ H13 Overheated / burnt 3.09 3.38* 3.44* 3.00 3.27 0.404 Cable and wiring H14 Mechanical damage 2.44 1.74 2.26 1.09 1.70 0.166 ▲ H15 Corroded metal parts 2.79 1.91 3.29* 1.15 2.12 0.237 ▲ H16 Damaged insulation 2.97 2.76 3.15 3.26* 3.06 0.363 H17 Damaged elec box 1.97 1.26 2.53 2.97 2.25 0.178 Distribution equipment H18 Unsafe switch-board or panel-board 1.79 1.53 2.50 2.00 2.01 0.144 ▲ H19 Burnt mark or smell in switchboard, panelboard 2.29 2.97 3.62* 2.00 2.86 0.263 ▲ H20 Outlet box unsafe 3.38* 1.85 2.53 3.35* 2.58 0.349 ▲ H21 Noise / spark 1.85 2.88 3.38* 3.06 3.11 0.230 H22 No power at receptacle 1.65 1.50 3.15 1.18 1.94 0.128 H23 Jam/ loose switchgear / switch 2.21 1.35 2.94 1.24 1.84 0.163 H24 Inaccurate meter 1.76 2.97 2.03 1.09 2.03 0.143 Protective device ▲ H25 Frozen / unable to trip 3.09 2.88 3.24* 4.00* 3.37 0.417 H26 Noisy contactor 1.74 1.91 2.76 1.18 1.95 0.135 Lighting ▲ H27 Lamps blink, flicker, freq blow off 2.32 2.12 2.97 3.41* 2.83 0.263 ▲ H28 Less light 2.03 3.59* 2.88 3.26 3.25 0.263 H29 No light 1.32 2.44 2.06 3.03 2.51 0.133 H30 Damaged casing 2.09 2.26 2.82 1.06 2.05 0.171 H31 Overheated / burnt ballast 2.12 2.26 2.76 1.09 2.04 0.173 H32 Noisy ballast 2.29 1.29 2.71 2.71 2.24 0.205 Standby / emergency power supply ▲ H33 Generator: noise, vibe & overheating 2.53 1.50 3.56* 2.47 2.51 0.254 ▲ H34 Dirty, leaky generator body 1.79 1.88 2.76 1.32 1.99 0.143 ▲ H35 Damaged insulation 1.38 1.35 3.03 3.26* 2.55 0.141 ▲ H36 No / delayed/ less power supply 1.50 2.76 1.53 4.74* 3.01 0.181 Grounding & LPS ▲ H37 Corroded parts 1.32 2.44 3.00 2.47 2.64 0.140 ▲ H38 No /poor conductivity 1.29 1.29 4.15* 3.65* 3.03 0.157 ▲ H39 Damaged electrode 1.71 1.32 2.76 2.97 2.35 0.161 Note: * Represents the t-value that is higher than critical t-value (1.6931) ▲ Represents critical defects Short circuit, poor output of equipment, nuisance tripping and burnt cable are responsible for both economic loss and poor system performance On the contrary less light output from luminaires is considered economic loss due to lower productivity Damaged insulation, frozen 122 protective device and poor conductivity of grounding and lighting protection system have significant impact on system performance and safety Additionally, loss of insulation, unsafe working condition, problem in emergency power supply etc were graded highly critical in terms of safety It should be noted that failure of protective device was considered the most critical defect among all followed by burnt cable and damaged insulation 4.11 Defects in fire protection system Fire hazards have been recorded since early dates of history starting from arson fire of Rome in 390BC (Nolan, 2001) Fire in buildings costs about 1% of GDP each year for developed nations (Cox, 1999) Contrary to its destructive nature of loss of life and property, such incidents have contributed in development of fire safety engineering Instead of traditional fire triangle of oxygen, fuel and heat, concept of fire quadrangle with the fourth element of chemical chain reaction has been introduced in development of extinguishers Similarly planning aspects such as efficient occupant evacuation and early detection or suppression of fire are being dealt with probability theory, risk assessment or decision tree (Ashe & Shield, 1999, Charters et al., 2002; Hasofer & Bruck, 2004) Fire protection engineering is multidisciplinary in true sense (Lataille, 2003) Architecturally it is the layout and planning of escape route, while fire rating of the construction is covered by civil engineering Mechanical aspects involve flow of water through the pipe work, discharge of extinguishing agent through nozzle and fluid mechanics Finally chemical engineering deals with hazards of chemical interaction and processes As reported by various studies (Burke, 2008; Fontana, Favre & Fetz, 1999; NFPA, 2008; Nolan, 2001), among many reasons, of fire hazards, a number of them were avoidable by addressing maintainability aspect and this thesis concentrates upon those issues In most of the cases the mistakes reported are, (1) exits not properly marked or blocked or locked; (2) no / inoperative alarm system; (3) missing fire hose, standpipe or extinguishers; (4) no sprinkler installed or sprinkler did not respond and (5) no fire training provided to occupants or maintenance team 123 Detector and alarm Dirty detector Mimic panel glass dirty with paints Fire hydrant, hose & portable fire extinguisher Knocked over Wall added later Hidden by landscape Glass broken in hose reel cabinet Haphazard winding Corroded hydrant Illegible label Misuse, wrong placing Obstructed sprinkler Broken pipe brace Rust & pitting in pipe Label is not permanent type - peeled off / Wrong locking, nonhomogenous panels & handwritten notice Fire exit obstructed from outside Sprinkler system Dirty, head rusty sprinkler Fire escape No light in exit sign Fig 4.11 Common defects in fire protection system Fire protection systems are required only during fire hazard and such hazard is a rare incident Hence unless a maintainability plan is adopted, there is a high possibility that during emergency it may remain inoperative Especially for non-sprinkled buildings, fire brigade relies upon fire hydrants As these are usually under the supervision of local water 124 department, it has a higher probability of being forgotten or being camouflaged by landscaping, parking or any other outdoor structure The common defects often faced by maintenance team in commercial buildings of Singapore are noted in Table 4.18 and the visible signs of defects are presented in Fig 4.11 Table 4.19 Common defects in fire protection system and their causes Defects & Coding Under performance or false alarm of detector (J1) Manual call point faulty (J2) Inaudible or unidentifiable alarm (J3) Alarm panel – no signal, spoilt exterior (J4) Difficult access / detection (J5) Faulty – leaky, jammed (J6) Unacceptable wkg condn (J7) Rusted riser (J8) Inlet jam (J9) Damaged hose– cut, kink, leak, missing part, abrasion (J10) Damaged nozzle (J11) Cabinet difficult to open (J12) Damaged cabinet (J13) Possible causes of defects Detection and communication Flame detector is misaligned, damaged by shock if loosely fitted Wrong selection (exposed to usual but high heat, smoke or light) Function not checked through simulation test after installation and during regular maintenance Obstructed or covered by paint– poor housekeeping Dirty - especially for poorly accessible points No power supply (unreliable power source, faulty wiring or battery goes flat) Wrong selection of bells –not distinguishable from general clutter Loose gong bolt or damaged alarm - blocked, corroded, spoilt by extreme temperature fluctuation Faulty alarm panel to indicate the exact alarm – no lucid diagram, corresponding bulb blown off or battery goes flat Proper connectivity to response centre is not provided Panel is tampered – lack of concern for safety or unsafe location Bulbs, buzzer etc can’t work if not reliable or battery goes flat Blown bulbs are not replaced Excessive damp location or poor make leads to corrosion of cabinet Fire hydrant and accessories Obstructed by parking, landscaping - poor project coordination Not installed at adequate height as per specification Damaged by corrosion, physical damage E.g knocked by vehicles Parts (stem, cap, plug, thread etc.) damaged during installation Corroded parts if not lubricated or painted at regular interval Outlet is not properly tightened after testing Missing operating nozzle – careless use, not secured Such examples are: dry riser having water or less pressure in wet riser It happens mainly if valves are faulty or leaky Poor make Cyclic wetting and drying if the tests are conducted carelessly Use of raw / dirty water Tanks may not be cleaned for long Dirt deposition in the rubber cap or breeching inlet Fire hose Misuse - washing floors or vehicles etc, mishandling Wear and tear with time Accelerated aging if of poor make Improper winding due to careless handling Velcro strap damaged Cause gr D C M E ▲ ▲ ▲▲ ▲ ▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲ ▲ Mishandling, careless maintenance E.g dislodged from stem or not ▲ connected to hose rack nipple or valve Jammed, obstructed if not cleaned properly or flushed out ▲ ▲ Hinges not lubricated, corroded from poor make especially if in ▲ ▲ extreme damp location Located in a place vulnerable to mechanical damage ▲ Glazing broken or glass break device missing due to vandalism ▲ 125 Defects & Coding No more functional (J14) Inadequate spray / discharge (J15) Leakage in pipe (J16) Blocked pipe (J17) Sagging pipe (J18) Pump- excess vibration, noise overheating (J19) Overflowing / leaky tank(J20) Leakage in vales (J21) Missing (J22) Auto valve is no more auto (J23) False alarms (J24) Preact & deluge valve - low discharge (J25) Missing / damaged parts or whole unit (J26) Possible causes of defects Sprinkler system Unsuitable choice of type and function of sprinkler makes it nonoperative within a short period of time Covered by paint or other foreign material Poor maintenance - dirty, damaged by use of wrong wrench Empty gas bulb – needs replacement with time Poor consideration for potential obstructions in planning Wrong orientation / hindrance by supports (careless installation) Obstructed by poor housekeeping – stacking of material Replaced with different type (usually if spare unit not in stock), grease / dirt in spray nozzle Excessive corrosion and scaling if pipe is not rust resistant No remedial measure taken for initial corrosion and pitting Microbiologically influenced corrosion (MIC) due to use of raw / untreated water, irregular flushing Excessive scale and sedimentation from raw water, inferior material or irregular flashing Misaligned, careless workmanship -tools, loose fittings left inside Effect of vibration, water flow etc not taken into account in design or mounting location is not enough strong Strength of supports were not cross checked during installation Pipe hanger and seismic brace become loose and worn with time No safe working condition or enough space in pump room for regular inspection, maintenance or replacement of pumps Insulating pad not provided to reduce noise and vibration Defects during installation remain unnoticed Pumps are not maintained regularly E.g cleaning, lubrication, inspection and testing Tank body not made of corrosion proof material Tanks not maintained regularly–sludge removal, overflow pipes etc Valves are not closed / opened fully if jammed from dirt or rust from poor material, raw water or irregular lubrication Valves damaged by mishandling E g use of wrong wrench Valves not properly closed or opened during maintenance/ after test Valves are misfit – usually due to wrong replacement Gasket / washer not aligned or wear and tear with time Theft of valve / parts such as hand wheel, padlock, strap etc Water pressure that regulates the valve is too low Should be detected by pressure gauge Leakage through rubber washer which is missing or groves dirty Retarding chamber or alarm drain leaking Supervisory switch tampered by vandalism or mishandling Pressure gauge has loose spring or worn out dial Accuracy of reading should be tested Pressure regulating valve or switch not calibrated after testing Rusting or wear / tear of flow switch tongue giving wrong signal Misfit flow switch – usually during replacement Drop in supervisory air pressure due to leakage at jointing Diaphragm not opening full if rusted, dirty (esp use of raw water) Cause gr D C M E ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲ Portable fire extinguisher Corroded if not rust resistant or exposed to very damp environment ▲ ▲ Denting or abrasion due to mishandling ▲ Mishandling may damage parts (seal trap, thread, gasket, handle etc) ▲ Stolen – vandalism Mounting should be able to prevent that ▲ ▲ 126 Defects & Coding Wrongly placed (J27) Less pressure in nozzle or poor discharge (J28) Unacceptable extinguishing agent - needs change or unsuitable discharge (J29) Faulty puncture mechanism(J30) Door not fully closing/ opening (J31) Damaged doorpanel, label, glass broken etc (J32) Faulty door release (J33) No / less light for exit & sign (J34) Smoke curtain/ shutter half closed (J35) Insufficient ventilation (J36) Possible causes of defects Hangers are broken due to corrosion, not secured to structure or used for hanging heavier extinguisher No concern for safety rules, misuse e.g as door stopper Irregular servicing - leaky pressure valve, poor content of extinguishing agent or clogged by the dated agent Damaged nozzle such as cracked, deformed, spoilt thread etc from mishandling or vandalism Mounting not vandal proof Illegible weight marking may leave gas cartridge partially empty Extinguisher if not hydrostatically tested, may not be suitable to cater to the full pressure Leakage due to corrosion of inferior quality pipe material Hardening of powder in damp environment Water / foam has incorrect weight or of expired date Liquid become gummy if not changed in time and clogs the pressure vacuum vent or the discharge nozzle Malfunction of components with time - suppression activator, proportioning device etc Should be replaced as recommended Components of nozzle cap, plug etc corroded, missing or misaligned A change in type is required to suit the anticipated type of fire and hazard class Usually happens due to change in building use Poor make Thread is blunt or jammed - damaged during installation / servicing Fire escape & related services No /faulty self closure (usually damaged if no cushioned back check Not set to operate with minimum force Jammed/sagging from poor wkmanship (e.g tilted hinge), rough use Stopper provided or obstructed due to structural member or stacking of material nearby Accuracy of gap should be maintained during all stages Accelerated aging due to poor specification or installed door differs from tested prototype Usually such doors have lower fire rating than expected Panels stripped off with time, rough usage or mishandling during installation A regular checking or minor repair is recommended Label is peeled off (not vandal-proof metal plate type) or covered during careless painting Labels are required for confusion free operation and maintenance Glass is not vandal proof or of larger area than recommended Faulty sensor - paint/coat on its surface or aging Corrosion of the link or hinges Lubrication helps Inadequate provision of lux level Bulbs dirty, blown or faulty starter /ballast Better to use LED Power source is not reliable- use of standby generator which fails mostly as controlled by mains Wrong circuit design or wiring – it is unable to switch on escape lighting when the normal power is switched off Regular testing and marking on DBs are recommended to avoid ambiguity Battery goes flat – over discharged or not charged properly, tampered, electrolyte condition not satisfactory or leaking Battery or light not working at all – if mounted in wrong position Careless maintenance After testing not reset into operating condition Parts are corroded / not lubricated - not operating smoothly Poor intake by fans which suffers from faulty installation, poor servicing or clogged ventilating screen Inadequate standby fan to compensate poor performance of duty fan Cause gr D C M E ▲ ▲ ▲ ▲▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲ ▲ ▲ ▲▲▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲▲▲ ▲▲▲ ▲ ▲ ▲ ▲▲ ▲ 127 4.11.1 Criticality analysis of defects in fire protection system Table 4.20 Criticality analysis defects in fire protection system Code Defects in fire protection system ⎯XFR ⎯XEC ⎯XSP Detection and communication ▲ J1 Under performance or false alarm of 2.68 2.32 2.97 detector J2 Manual call point faulty 1.53 2.44 2.26 J3 Inaudible or unidentifiable alarm 1.26 2.15 3.09 J4 Alarm panel – no signal, spoilt exterior 1.91 2.76 3.24 Fire hydrant and accessories J5 Difficult access / detection 2.00 2.53 2.91 J6 Faulty – leaky, jammed 1.68 2.00 3.24 ▲ J7 Unacceptable working condition 1.85 3.26 3.53* J8 Rusted riser 1.74 1.91 3.09 J9 Inlet jam 2.21 1.38 2.71 Fire hose ▲ J10 Damaged hose–cut, kink, leak, missing 2.03 2.44 3.56* part, abrasion ▲ J11 Damaged nozzle 1.32 2.38 3.29* J12 Cabinet difficult to open 1.85 2.26 3.03 J13 Damaged cabinet 2.53 2.94 3.15 Sprinkler system ▲ J14 No more functional 1.68 2.85 4.06* ▲ J15 Inadequate spray / discharge 1.32 3.53* 4.03* ▲ J16 Leakage in pipe 2.09 2.91 3.15 ▲ J17 Blocked pipe 1.29 2.74 3.56* J18 Sagging pipe 1.76 1.29 2.88 ▲ J19 Pump- excess vibration, noise overheating 1.97 1.53 3.59* J20 Overflowing / leaky tank 1.53 1.24 3.00 J21 Leakage in vales 1.82 2.97 3.09 J22 Missing 1.38 1.26 2.76 J23 Auto valve is no more auto 1.32 2.32 2.97 J24 False alarms 2.91 1.88 2.18 J25 Preact & deluge valve - low discharge 1.74 1.97 2.68 Portable fire extinguisher ▲ J26 Missing / damaged parts or the whole unit 2.06 2.38 3.62* J27 Wrongly placed 1.85 2.03 2.24 ▲ J28 Less pressure in nozzle or poor discharge 1.91 2.88 3.09 ▲ J29 Unacceptable extinguishing agent - needs 1.79 2.44 3.29* change or unsuitable discharge J30 Faulty puncture mechanism 1.76 1.91 3.03 Fire escape & related services ▲ J31 Door not fully closing/ opening 2.06 2.32 3.06 J32 Damaged door- panel, label, glass broken 2.26 2.35 2.76 etc ▲ J33 Door release device faulty 1.88 2.35 3.21 ▲ J34 No / less light for exit & sign 1.88 2.38 2.76 J35 Smoke curtain/ shutter half closed 1.53 2.29 3.09 ▲ J36 Insufficient ventilation 1.15 2.32 2.76 Note: * Represents the t-value that is higher than critical t-value (1.6931) ▲ Represents critical defects ⎯XHS Sv Cr Rnk 3.50* 2.93 0.314 0.314 3.29 2.79 3.06 2.67 2.68 3.02 0.163 0.135 0.231 0.163 0.135 0.231 2.97 3.00 3.03 2.53 2.62 2.80 2.75 3.27 2.51 2.24 0.224 0.184 0.243 0.174 0.197 0.224 0.184 0.243 0.174 0.197 2.97 2.99 0.243 0.243 2.82 3.03 2.47 2.83 2.77 2.85 0.150 0.206 0.289 0.150 0.206 0.289 4.79* 3.21 3.59* 3.15 2.53 1.32 1.24 1.18 1.15 1.26 1.68 1.12 3.90 3.59 3.22 3.15 2.24 2.15 1.82 2.41 1.73 2.19 1.91 1.92 0.262 0.190 0.269 0.163 0.158 0.169 0.112 0.176 0.095 0.116 0.223 0.133 0.262 0.190 0.269 0.163 0.158 0.169 0.112 0.176 0.095 0.116 0.223 0.133 4.68* 2.50 3.47* 3.76* 3.56 2.25 3.15 3.17 0.293 0.167 0.241 0.227 0.293 0.167 0.241 0.227 2.88 2.61 0.184 0.184 4.68* 2.91 3.35 2.68 0.276 0.242 0.276 0.242 3.32* 3.56* 3.21 4.41* 2.96 2.90 2.86 3.17 0.223 0.219 0.175 0.145 0.223 0.219 0.175 0.145 Though 44% of defects were found critical, not a single one was frequent Economic loss was attached to inadequate discharge of sprinklers causing loss of property Dysfunction of sprinkler or portable fire extinguisher and unacceptable quality of extinguishing agent were found affecting both system performance and safety Rest of the critical defects related to system performance were unsuitable working condition of hydrant, damaged fire hose and 128 problems with pump However in the safety criticality group, false alarm, leaky sprinkler pipe, missing extinguisher, incomplete opening or closing of fire door, faulty catch device and poor ventilation of escape route were mentioned These defects can bring disaster even during a small incident of fire However it should be noted that detection of fire is the first step of active fire protection system and evidently it was ranked highest in the criticality list 4.12 Comparison of causes and criticality of building subsystems A total of 319 different types of defects were detected for nine subsystems 95 (29.7%) of them are in civil-architectural or C&A and rest for mechanical-electrical or M&E subsystems which have much higher number of components Design in general was responsible for more than 70% defects with an average of 86% (Fig 4.12a) Similarly, construction / installation, maintenance and external factors were associated with average of 69%, 68% and 29% of defects However a straight forward ratio of importance of these four causes cannot be drawn due to two reasons Firstly, these numbers include defects with multiple causes and chain effects of defects up to two levels Secondly, the impacts of these four factors are very different for different subsystems (Fig 4.12a) For instance, facade and wet area have many choices of finishes which in turn determine their performance (water tightness, cleanability, appearance) Hence design bears a very high importance in this case On the contrary, elevators and fire protection system rely on standard products already designed and tested by certified manufacturers and selected as per requirement Hence scope of individual design is very less and as a result design related errors are also very less For the same reason, C&A subsystems have higher (8% in average) emphasis on design compared to M&E subsystems Similarly, 28% and 60% higher emphasis was given to construction and external factors for C&A subsystems as they are constructed at site unlike M&E elements which as produced at factory with high quality control and installed at site Also C&A components suffer from external factors of exposure, usage and vandalism Wet area was revealed to be the worst 129 100 % of Total defects 90 80 Design spec 70 60 Const./ install 50 40 Maintena nce 30 20 Ext factor 10 C&A Fire prot Electrical Elevator HVAC Sanplumb Roof Wet area Faỗade Basement M&E a Comparison of causes of defects 80 % of total defects 70 60 Cr 50 FR 40 EC 30 SP 20 HS 10 C&A Fire prot Electrical Elevator HVAC Sanplumb Roof Wet area Faỗade Basement M&E b Comparison of effects w.r.t total defects % of Critical defects 80 70 60 50 FR 40 EC 30 SP 20 HS 10 C&A Fire prot Electrical Elevator HVAC Sanplumb Roof Wet area Faỗade Basement M&E c Comparison of effects w.r.t critical defects Note: Cr= critical defects; FR= frequent defects; EC= defects with significant economic impart; SP= defects with significant system performance impact; HS= defects with significant health-safety-comfort impact Fig 4.12 Comparison of defect causes and criticality of nine subsystems 130 sufferer (52%) due to constant exposure to water and constant usage Fire protection system scored highest (30.6%) among M&E group in spite of its rare usage The reason is its many components (e.g hydrant, breeching inlet etc) are externally located making them vulnerable to the climate and misuse Sometimes misuses are unintentional, e.g., buried by landscaping In terms of maintenance, M&E systems are 81.4% (84.4 vs 46.6 of average nos of defects) more sensitive due to higher number of components and direct operation by occupants Table 4.21 Average % of defects for C&A and M&E systems System C&A M&E Total defects 41.34 58.66 Critical 37.61 62.39 Frequent 70.17 29.83 Economy 59.89 40.11 Sys perf 37.20 62.80 Hlth-sfty-cmft 31.01 68.99 Effects or criticality of the defects are presented in Fig 4.12b & c Four criticality parameters namely frequency of occurrence, economic impact, system performance impact and healthsafety-comfort impacts are used to find % of defects w.r.t total and critical defects From Table 4.20, it can be evaluated that out of 319 total defects 145 (45.5%) are critical of which 89 (61.4%) are M&E contributions C&A defects are 135.2% more frequent (30% for C&A, 70% for M&E) and C&A defects also have 49.3% more impact on economy However system performance for M&E systems is 68.8% more important than C&A systems (62.8% vs 37.2%) and direct impact through health-safety-comfort is 222.5% of C&A systems 4.13 Summary This chapter has presented a comprehensive defect list pertaining to nine major subsystems in buildings along with the analysis of causes and criticality of effects and critical defects were short-listed Hence the first research objective of defect databse is achieved and it provides answer for the first research question i.e ‘What affects maintainability and how they influence?’ This information will be used in next chapter to determine the relative weights of defect-mitigating maintainability factors This analysis also highlighted the general characteristics of C&A and M&E systems 131 ... 1.94 2. 35 2. 09 1.06 1 .21 2. 88 2. 26 2. 44 2. 03 2. 68 2. 35 3.03 1 .26 2. 32 2.44 2. 62 2. 82 2. 62 3.09 1.09 1.06 2. 88 3.00 3.35* 3.15 3.15 4. 82* 4.65* 2. 09 2. 70 2. 57 2. 80 2. 67 2. 81 3. 42 2. 92 1.47 0 .25 1... 1.38 2. 22 1.56 1.78 0.0 82 0.188 0.084 0.073 0.0 62 0.150 0.069 0.065 0.130 0.084 0.174 1 .24 2. 06 2. 76 1. 12 3.59* 1.18 2. 12 2.70 1.71 0 .29 4 0 .22 2 0.155 3.41* 1. 32 1.74 1. 32 2.73 2. 06 0 .26 6 0 .27 4 2. 71... 2. 56 2. 88 2. 53 3.91* 3.17 2. 35 3.66 3 .27 3.77 0.354 0.360 0. 323 0.404 0 .24 4 1.94 1.50 1.69 0.167 2. 82 2.18 1.35 1.50 1.74 1. 32 1 .29 1.88 2. 12 2 .21 1 .24 1.65 1.47 1 .26 1.18 1.47 1 .26 1. 32 2 .24 2. 79