Building Services Engineering 5th Edition Handbook

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Energy economics 53 Table 2.10 Cash flow forecast for the leasing of an energy-economizing equipment. Year 1 Year 2 Year 3 A Cash balance brought forward 0 157 500 270 375 B Leasing payment, 10% × cost (50 000) (50 000) (50 000) C Energy saving 200 000 210 000 220 500 D Capital allowance 0 0 0 F Cash balance (A − B + C + D) 150 000 317 500 440 875 F Interest, say 10% × E × 0.5 7500 15 875 22 044 G Tax, 40% × (C + F − B), 1 year in arrears 0 (63 000) (70 350) H Net cash flow (C + D + F − B − G) 157 500 112 875 122 194 I Cash balance (A + H) 157 500 270 375 392 569 rather than purchased, and this releases cash earlier but calls for continuous payments to the leasing company. Table 2.10 shows a sample cash flow forecast. Cash flow is always positive to the company, but leasing payments are made for 10 years and then at a reduced rate after that period. Self-contained items of plant such as heat pumps or electricity generators may be leased. Low-energy buildings Low-energy buildings are those that utilize energy efficiently to maintain a comfortable thermal environment suitable for the purpose of the building. Design software for steady-state and dynamic use of the building are available from many sources such as the Building Regulations, Building Research Establishment Environmental Assessment Method, BREEAM, Leadership in Energy and Environmental Design, LEED, Green Star and Greenhouse Rating schemes, and are applied variously to the design stage and also during the service period of the building to meet agreed standards. Energy design targets may be proposed that include uses for heating, ventilation, hot-water services, lighting and electrical power. The total demand target T for a building is assessed by adding the thermal demand target T T to the electrical demand target T E in the CIBSE Building Energy Code (CIBSE, 1981). In heated and naturally ventilated buildings, the rate of heat loss is related to the floor area by the dimensionless building envelope number B: B = A w A f + K 1 n f + K 2 H where A w is the gross external walling surface area (m 2 ), A f is the total floor area (m 2 ), n f is the number of storeys and H is the floor-to-ceiling height (m). When hot-water services are included: T T = C 1 B + C 2 W/m 2 where K 1 , K 2 , C 1 and C 2 are constants given in Table 2.11, C 3 is the mean electrical power requirement for the lighting system (W/m 2 ) and, T E = C 3 + 0.10T T W/m 2 which shows that the electrical power consumption associated with the heating services is expected to be 10% of the thermal target.
54 Energy economics Table 2.11 Values of constants for demand target. Building type K 1 K 2 C 1 C 2 C 3 Office, 5 days/week 0.5 0.1 13 −5 24 Shop, 6 days/week 0.5 0.1 16 −6 27 Factory, 5 days/week, single shift 1.1 0.2 6 3 8 Hotel 1.0 0.1 15 −3 15 Warehouse 1.1 0.2 6 −2 6 Hospital 1.0 0.1 17 +12 15 Institutional residence 1.0 0.1 15 ±4 15 Educational 0.5 0.2 16 −4 13 EXAMPLE 2.14 Find the total demand target for a proposed 10-storey hospital medical building 50 m long, 30 m wide and 3 m floor-to-ceiling height, and compare it with an alternative design having the same floor area but of single-storey design, 172 m long and 87 m wide. Comment on the relative energy use of these alternative configurations. For the 10-storey block A f = 50 × 30 × 10 m 2 = 15 000 m 2 A w = 10 × 3 × 2 × (50 + 30) m 2 = 4800 m 2 n f = 10 H = 3m From Table 2.11, K 1 = 1 and K 2 = 0.1. Then: B = 4800 15 000 + 1 + (0.1 × 3) 10 = 0.72 Also from Table 2.11, C 1 = 17, C 2 =+12 and C 3 = 15 W/m 2 . Then: T T = (17 × 0.72 + 12) W/m 2 = 24.24 W/m 2 T E = (15 + 0.1 × 24.24) W/m 2 Thus: = 17.4 W/m 2 T = T T + T E = (24.24 + 17.4) W/m 2 = 41.6 W/m 2
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Building Services Engineering
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Building Services Engineering Fifth
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Contents Preface to fifth edition A
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Contents vii Sick building syndrome
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Contents ix Circuit design 294 Cabl
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Preface to fifth edition Building S
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Acknowledgements I am particularly
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Units and constants xv Table 2 Mult
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Symbols xvii Symbol Description Uni
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Symbols xix Symbol Description Unit
Page 23 and 24: 2 Built environment Introduction Th
Page 25 and 26: 4 Built environment Ventilation The
Page 27 and 28: 6 Built environment (a) At full occ
Page 29 and 30: 8 Built environment Table 1.2 Compa
Page 31 and 32: 10 Built environment Because of the
Page 33 and 34: 12 Built environment Visual display
Page 35 and 36: 14 Built environment v = 7 m/s t a
Page 37 and 38: 16 Built environment 1.4 Sling psyc
Page 39 and 40: 18 Built environment 1.7 Thermistor
Page 41 and 42: 20 Built environment t res = t g (1
Page 43 and 44: 22 Built environment great care wit
Page 45 and 46: 24 Built environment 16. An hotel l
Page 47 and 48: 26 Built environment 37. Are any of
Page 49 and 50: 28 Built environment building has a
Page 51 and 52: 30 Built environment 73. What was t
Page 53 and 54: 32 Energy economics Introduction Bu
Page 55 and 56: 34 Energy economics 16. air-to-air
Page 57 and 58: 36 Energy economics 1 kWh = 1 kWh
Page 59 and 60: 38 Energy economics 2. Heat transfe
Page 61 and 62: 40 Energy economics For solid fuel
Page 63 and 64: 42 Energy economics gas cost = 1.80
Page 65 and 66: 44 Energy economics Table 2.5 Carbo
Page 67 and 68: 46 Energy economics EXAMPLE 2.8 A h
Page 69 and 70: 48 Energy economics annual cost = u
Page 71 and 72: 50 Energy economics EXAMPLE 2.12 Ex
Page 73: 52 Energy economics l = 0.035 ( 1 0
Page 77 and 78: 56 Energy economics From Table 2.4
Page 79 and 80: 58 Energy economics 3. Minimum outs
Page 81 and 82: 3 Heat loss calculations Learning o
Page 83 and 84: 62 Heat loss calculations Table 3.1
Page 85 and 86: 64 Heat loss calculations Table 3.6
Page 87 and 88: 66 Heat loss calculations Where onl
Page 89 and 90: 68 Heat loss calculations The venti
Page 91 and 92: 70 Heat loss calculations The surro
Page 93 and 94: 72 Heat loss calculations The speci
Page 95 and 96: 74 Heat loss calculations where R m
Page 97 and 98: 76 Heat loss calculations The addit
Page 99 and 100: 78 Heat loss calculations operation
Page 101 and 102: 80 Heat loss calculations 2. The fo
Page 103 and 104: 82 Heat loss calculations internal
Page 105 and 106: 84 Heat loss calculations 27. Which
Page 107 and 108: 86 Heating Key terms and concepts a
Page 109 and 110: 88 Heating 4.2 Electrically heated
Page 111 and 112: 90 Heating Sheet steel case Removab
Page 113 and 114: 92 Heating Floor finish Screed with
Page 115 and 116: 94 Heating Flue Return air plenum F
Page 117 and 118: 96 Heating Table 4.1 Classification
Page 119 and 120: 98 Heating Table 4.2 Heat output fr
Page 121 and 122: 100 Heating Table 4.3 Flow of water
Page 123 and 124: 102 Heating and, maximum available
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104 Heating This means that one vol
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106 Heating Performance testing A r
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108 Heating Electrical power genera
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110 Heating Combined heat and power
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112 Heating 3. A building energy ma
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114 Heating Connections are made to
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116 Heating remotely the MWh consum
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118 Heating 13. The two-pipe heatin
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120 Heating 27. Which is not correc
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122 Heating 39. Which of these is t
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124 Heating 4. Heat supplied is cha
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126 Ventilation and air conditionin
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6 Hot- and cold-water supplies Lear
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180 Hot- and cold-water supplies Wa
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182 Hot- and cold-water supplies po
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184 Hot- and cold-water supplies Ce
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186 Hot- and cold-water supplies st
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188 Hot- and cold-water supplies 0.
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190 Hot- and cold-water supplies 53
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192 Hot- and cold-water supplies an
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194 Hot- and cold-water supplies Ta
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196 Hot- and cold-water supplies Ta
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198 Hot- and cold-water supplies (a
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204 Hot- and cold-water supplies 49
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206 Soil and waste systems Introduc
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208 Soil and waste systems Open to
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210 Soil and waste systems 7. Bends
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212 Soil and waste systems The inte
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214 Soil and waste systems 40 mm wa
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216 Soil and waste systems Table 7.
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218 Soil and waste systems 50 mm ve
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220 Soil and waste systems 3. Long
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222 Surface-water drainage Table 8.
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224 Surface-water drainage Rectangu
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226 Surface-water drainage The solu
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228 Surface-water drainage 7. A PVC
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230 Below-ground drainage Design ca
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232 Below-ground drainage Manhole:
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234 Below-ground drainage From Fig.
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236 Below-ground drainage storage v
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238 Below-ground drainage 14. The f
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240 Condensation in buildings mould
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242 Condensation in buildings The w
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244 Condensation in buildings EXAMP
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246 Condensation in buildings This
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248 Condensation in buildings Tempe
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250 Condensation in buildings and,
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252 Condensation in buildings EXAMP
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254 Condensation in buildings Tempe
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256 Condensation in buildings For t
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258 Condensation in buildings 4. Ev
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11 Lighting Learning objectives Stu
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262 Lighting Table 11.1 Typical val
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264 Lighting Light sources 9 9 9 Wi
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266 Lighting Utilization factor The
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268 Lighting From Table 11.3, for a
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270 Lighting Table 11.4 Lamp data.
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272 Lighting number of lamps = 12.8
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274 Lighting 3. Sketch and describe
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276 Lighting 4. Insufficient inform
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278 Lighting 3. 800 lm/m 2 . 4. 260
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12 Gas Learning objectives Study of
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282 Gas Open to atmosphere Rubber p
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284 Gas EL = (1.25 × 34) m = 42.5
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286 Gas become exhausted. SNG will
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288 Gas are ignited and an air flow
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290 Gas 3. The pipe from a gas mete
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292 Electrical installations Key te
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294 Electrical installations curren
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296 Electrical installations 1 Volt
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298 Electrical installations power
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300 Electrical installations For1mm
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302 Electrical installations Table
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304 Electrical installations Incomi
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306 Electrical installations energi
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308 Electrical installations Starte
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310 Electrical installations Ethyle
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312 Electrical installations Test o
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314 Electrical installations Joint
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316 Electrical installations 4. 100
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318 Electrical installations 39. Wh
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320 Electrical installations 51. Wh
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322 Room acoustics 20. understand t
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324 Room acoustics pump blades and
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326 Room acoustics ceiling, Q is 4.
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328 Room acoustics Table 14.2 Solut
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330 Room acoustics Table 14.3 Fan s
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332 Room acoustics Table 14.4 Illus
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334 Room acoustics (Sound Research
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336 Room acoustics The target room
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338 Room acoustics Table 14.6 Noise
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340 Room acoustics 100 90 80 70 Sou
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342 Room acoustics 24. A forced-dra
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344 Room acoustics The room directi
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346 Room acoustics 3. Multiple sour
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348 Room acoustics 55. Which is not
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350 Fire protection computer monito
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352 Fire protection halogen gas, wh
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354 Fire protection the reach of tu
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356 Fire protection Range pipe Spri
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358 Fire protection Fire compartmen
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360 Fire protection 16. Which are c
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362 Plant and service areas Key ter
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364 Plant and service areas 2.0 1.5
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366 Plant and service areas Fuel st
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368 Plant and service areas a minim
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370 Plant and service areas An unde
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372 Plant and service areas Air cha
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374 Plant and service areas 100 mm
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376 Plant and service areas Fire co
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378 Plant and service areas Table 1
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380 Plant and service areas 11. Wha
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17 Mechanical transportation Learni
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384 Mechanical transportation Table
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386 Mechanical transportation Crowd
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388 Mechanical transportation Hydra
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390 Mechanical transportation 4. Co
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18 Question bank Learning objective
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394 Question bank 8. Which correctl
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396 Question bank 5. This building
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398 Understanding units Questions 1
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400 Understanding units 15. Which i
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402 Understanding units 29. Which o
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404 Understanding units 43. Which i
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Appendix: answers to questions Chap
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408 Appendix Chapter 3 Heat loss ca
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410 Appendix 4. 0.007469 kg H 2 O/k
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412 Appendix 32. 5 33. 5 34. 3 35.
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414 Appendix 23. Lighting 1200 h/ye
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416 Appendix 27. 37 dB. 28. 39 dB.
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418 Appendix 15. 5 16. 2 17. 5 18.
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References Action Energy, Departmen
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Index Absorption 154, 324 Absorptio
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424 Index Gas burner controls 289 G
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426 Index Sensible heat gains 137 S
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