T022 Design Economics

Mind Map by , created over 6 years ago

T022 & T074 Mind Map on T022 Design Economics, created by alison_patey0437 on 04/27/2013.

Created by alison_patey0437 over 6 years ago
Quantification and costing of construction works
Quantification and costing of construction works
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T022 Design Economics
1 NRM 1 Estimating
1.1 Purpose of an Order of Cost
1.1.1 relates to RIBA A/B & OGC Gateway 1 (business justification) 2 (delivery strategy) RIBA A/ Gateway 1 identify clients needs - prepare feasibility RIBA B/Gateway 2 iden. client brief/procurement method/ other consultants engaged
1.1.2 Est. proposed building project affordability
1.1.3 Est. a cost limit Max expenditure a client is willing to make
1.1.4 May be a need for alternative scenarios = cost options
1.1.5 Information Required fro OofC From Employer location statement of bdg use life span details of enabling wrks initial design brief requirements 4 refurb floor areas site conditions budget/cashflow constraints restraints e.g. planning/stat auth/listed bdg other e.g. CA/ land remediation From Architect sketches e.g. floor plans/ elevation/ sections Sch of areas e.g. GEA/ GIFA/ NIA Min storey height/ sch accomodation suggested ground conditions indicative services initial risks
1.1.6 Process of OofC 1. facilitating wks est. 2. Building wrks est. 3. MC prelims they define the scope of the works inc. proj particulars, list of dwgs, des of site, Preliminaries sections A54 - Prov sums; A10 Proj particulars Considerations when assessing preliminaries length of contract location - access/ space res/ accomodation type of proj: refurb/ new build/ large tower size of proj need 4 temp wrks security sectional completion avalibility of services 4. Sub total 5. MC OH&P 6. Works Cost Estimate total 7. Proj/Design team fees 8. Sub-total 9. Other Dev/proj. cost est. 10. Base cost est. total Base Cost Estimate total Bdg wks + MC prelims + MC OH&P + Prj/design fees + other dev est. 11. Risk Allowances estimate 4 nr risk allowances design dev construction risks emp. change risk emp. other risk allowance 4 risk & inflation r calc seperatley + add 2 base cost 2 determine cost limit 12. Cost Limit total (excl Inflation) 13. Tender inflation est. you review inflation through the use of TPIs tender price index TPI reflect changes in level of pricing in lowest accepted tenders for new wks 2 take account of market cond. - compares with base date 14. Cost limit total (excl. construction inflation) 15. Construction inflation est. 16. Cost limit total (inc Inflation)
1.2 Measurement rules for Building Works
1.2.1 Floor area Method Quants determined by measuring the GIFA Measured & multiplied by an appropriate £/m2 c = a x b a = GIIFA; b = cost/m2 of GIFA; c = Building cost estimate GIFA in accordance with RICS code of measuring practice 6th ed where building comprises of more than one bdg function = GIFA of each function calc seperately you can then delineate party walls etc. Ext wks measured separately as SA (Site Area)
1.2.2 Functional Unit method units of measurement used to represent a prime use each function inc necessary circulation space Cost/ hotel rm; cost/ school child; cost/ hospital bed c = a x b a = no. of functional units; b = £/functional unit; c = building works estimate
1.2.3 Elemental method alt approach 2 calc total est cost of bdg wks considers maj elements and provides an OofC based on the breakdown of other similar buildings cat. into group elements and elements 0 - Facilitating works 1 - substructures ELEMENT: Substructure 2 - superstructures ELEMENT: frame/ U.floors/ roof/ stairs & ramps/ Ext walls/ Windows & ext doors/ Int walls & partitions/ Int doors 3 - Internal finishes ELEMENT: wall/ floor/ ceiling finishes 4 - FF&E 5 - Services ELEMENT: Sanitary/ equip/ disposal/ water/ heat/ space heat & AC/ ventilation/ Electrical/ Fuel/ Lift/ Fire+lightning protection/ com, security & co 6 - prefab bdgs 7 - wks 2 ext bdg 8 - ext wks c = a x b a = EUQ; b = EUR; C = cost target used for RIBA C or OGC Gateway 3A provides a basis of the formal cost plan 1 EQR/EUR s/s by more detailed measure of elements
1.3 Measurement Rules
1.3.1 MC prelims added as a % derived from a considered assessment of cost analyses of previous bdg proj. subbies Prelims are normally inc into unit rates A list of MC inc in part 9 of NRM 1 they define the scope of the work
1.3.2 MC OH&P added as % derived from a considered assessment of cost of previous bdg proj. a list is inc in part 10 of NRM1
1.3.3 Proj/design fees either inc/exl list of fees in part 4 of NRM 1 added as a %
1.3.4 other dev/proj costs e.g. insurances/ planning fees/ fees 4 party walls etc. added as a lump sum acertained in conjunction with client
1.3.5 Risk risk exposure - as the design dev = more of proj defined & a risk response decided risk avoidance seriousness of risk consequences on proj is unacceptable measures inc review of brief/ re-design risk reduction level of risk unacceptable Action would be to reduce by: redesign/ further site investigation/ diff mat/ diff method of con/ change contract strategy Risk Transfer accepting risk would not be client value 4 money transfer 2 a 3rd party higher premium e.g. insurance cover Risk Sharing client retains some risk Risk retention risk retained by client = called residual risk risk allowances should NOT be a % but a properly considered assessment of the risk taking in 2 account completeness of design + other uncertainties Allowances should be made for the following Design Development risk e.g. planning/ legal/ covenants/ 3rd party risks Construction Risk e.g. site conditions/ access restrictions/ boundaries/ extg bdgs Employer change risk e.g. chg in scope/ quality/ time Employer other risks e.g. early handover/ acceleration/ avalibility of funding allowance should be made based on formal analysis e.g. risk register and Monte Carlo simulations
1.3.6 Inflation its possible to consider future effects of inflation on the base cost est. over a period of time to date of tender t = CL x p p = % tender inflation (published indices TPI), BCI or retail price indices (RPI) or % derived from in-house sources CL = cost limit; p = % for tender inflation; t = tender inflation estimate mid-point of construction c = CL x p CL = cost limit (ex const infla); p = % 4 const infla; c = construction inflation est
1.3.7 VAT is complex and recco excluded from OofC
2 NRM 1 Cost Planning
2.1 Purpose of cost planning
2.1.1 intrinsic with RIBA C/D, E/F & OGC gateway 3A & 3B RIBA stage C & Gateway 3A concept: implement concept design and outline proposals 4 structural & building services, outline spec, formal cost plan 1 RIBA stage D Design development: update design, planning, completion of brief RIBA Stage E & Gateway3B Technical Design: prep of tech design and spec 2 coordinate components and elements of proj & info for stat standards RIBA Stage F Production Info: prep info ready for tender
2.1.2 main purpose ensure emp. are provided with value for money make clients & designers aware of cost consequences of their desires/ proposals provide advice 2 designers to help them arrive 2 practical designs withn budget keep expenditure within cost limit robust cost info which the client can use 2 make informed decisions
2.2 Elemental cost planning/ cost planning
2.2.1 budget breakdown of the cost limit into cost targets for each element
2.2.2 its a statement of how the proj team proposes to distribute the availible budget amougst the elements of the building
2.2.3 its an iterative process which is performed in steps of inc detail as design develops
2.3 Constituent of a cost plan
2.3.1 it takes the same shape as the cost estimate
2.4 Formal cost plan stages
2.4.1 formal cost plan 1 = RIBA stage c
2.4.2 Formal cost plan 2 = RIBA stage D
2.4.3 Formal cost plan 3 = RIBA Stages E & F
2.5 Cost control in procurement
2.5.1 CP become a important cost control mechanism when work is procured by the use of seprate wk pack
2.6 Reporting of elemental cost plans
2.6.1 cost expressed as £/m2
2.6.2 items in CP reports 1. Exec summary/ prj title/ description/ status of CP 2. statement of cost inc cost limit 3. details of info/ spec on which CP was prepared/ statement of floor areas 4. Cost Plan 5. assumptions/ base date/ reason for change from previous CP 6. VE options/ conclusion/ recommendations 7. inclusions & exclusions
3 State of the construction market
3.1 Trends and forecasts 2013
3.1.1 Tender price index The second half of 2012 saw prices come under renewed pressure. 2013 little respite
3.1.2 Building cost index Employers faced higher wage bills at the end of last year and will have to fund a small wage increase at the beginning of 2013
3.1.3 Retail price index Higher utility costs caused retail prices to move back up. Higher food prices coming through will stop consumer price measures falling towards target.
3.1.4 Generally 2012 ended with construction prices continuing their slide Provisional fig 4 4thQ GDP = economic activity fell by comparison with 3rdQ, = Speculation trple dip recession (NB* confirm narrow avoidance) Deloitte CFO survey 2013: market has cautious optimism The Bank of England held interest rates at 0.5% since 03/09 & some suggest they will stay until 2017. The Autumn Statement 12/12 recog need 2 restore capital spending & announced an add £5bn of investment for roads, rail and edu Infrastructure pipeline: 550 projects est. @ £330 billion to 2015 An xtr 50 proj compared 2 2011 & £70m problem: gov think 85% will be privately funded BofE 4thQ Credit survey: banks offereing more cheaper credit due to the funding 4 lending scheme downside: bank reduced interest on savings - no need 2 attract savers money Construction products Assoc: lowered expectations of construction output 4 2013/14 trimmed by more than 4% The recently released Construction Skills annual report does not anticipate a return to the 2007 levels of construction activity until 2022. competition will remain intense keeping a lid on underlying cost inc A prediction of MC turning down works due to slim est depart - picking job 2 put effort into rather than buying jobs at a loss Material cost increases are likely to remain subdued in 2013 EUROPE (IMF) forecasting a further small contraction (-0.2%) for the Eurozone, before achieving a small 1.0% inc GLOBAL Global economy: stabilise in 2013; Global economic growth not expected 2 pick but neither slow again. weak Eurozone & slow Japan offset US growrh US should pick up if uncertainty of fiscal cliff & debt reduction is resolved China: regain momentum in 13 & surpass 8% growth Emerging market construction growth to lead the industry construction demand is likely to be highest in high risk areas, including Latin America, Africa and the MENA region.
4 Economics of design
4.1 Wall: Floor ratio
4.1.1 relationship between wall and floor
4.1.2 Shows efficiency of a bdg
4.1.3 Lower the ratio = cheaper the bdg
4.2 The most efficient bdg shape is a circle but has poor lettable area = square is best
5 Sources of cost info
5.1 In-house historical data
5.2 BCIS
5.3 Cost indices
5.4 cost analyses published in trade journals
5.5 Price books SPONS/LAXTONS
5.6 Building cost models
5.7 Sub-contractors & Suppliers

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