building cost planning assignment 2
TRANSCRIPT
Building Cost Planning
Mikkel Jorgensen
1
Building Cost Planning
Assignment 2
‘Sketch Design and Life Cycle Costing’
Trimester 3, December 10 2014
Student No. 214305185
Mikkel Jorgensen
Pages
Words
(Excludes front-page and reference list)
Building Cost Planning
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2
Table of content
Introduction 3
1. Part I: Sketch Design Costing 4
Bpi adjustment 5
1.1 Sketch Design Alternative One 6
1.2 Sketch Design Alternative two 7
1.3 Elemental cost alternative one 8
1.4 Elemental cost alternative two 9
Comparing 10
Recommendations 10
2. Part II: Life Cycle Costing 11
2.1 Option A 11
2.2 Option B 11
2.4 Option B 12
Recommendation 3% 13
Recommendation 6% 13
References 17
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Introduction
After the design team and the client have reviewed the schemes and the estimated prices first
presented. I have been required to give more information regards to scheme A. It is my
responsibility to collect the envelope cost of scheme A and create 2 different alternatives on how to
build the envelope.
Part 1, my aim with this Sketch Design costing and life cycle report is to determine how much the
envelope will cost, doing different circumstances. I will present two options and come up with the
best solution to get the most value for money by creating awareness of the cost consequences of
different solutions.
Part 2, Later I will look into the information provided regarding the life cycle cost of a curtain wall
doing different circumstances,
The information provided will make reason for my calculation of the lifecycle cost of the different
options and then I will come up with the best recommendation of the different alternatives
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1. Part I: Sketch Design Costing
This cost report deals with the development of a 7-story office building at a site in Geelong CBD.
The floor to floor height is initially determined at 4.00 meters. Throughout preliminary elevations in
the scheme shows the following:
Floor to ceiling height windows
The level one will contain the offices / showrooms and will have 75 % of the wall glazed
Level 2 to 7 show that 75 % of the total wall area is solid
Below I have prepared an elemental cost for two different design solutions of the envelope. The
envelope consist of the following three elements in both options:
External wall
Windows
Roof
I will come up with two different alternatives on how to construct the envelope with different
materials. Later in the report will I do my recommendation about which alternative would be the
best option
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Bpi adjustment
In order to establish the builders price index (BPI) for the expected tender date of the project
(December 2015) this table has been created. The historical bpi data has been sourced from
Rawlinson’s 34th edition 2014. Using the data’s I have calculated the change in the BPI from year to
year, this made it possible to forecast the price on the projects tender date in December 2015
As shown in the table. The difference from Rawlinson’s 34th edition 2014 the latest known BPI was
December 31, 2013 this gave me an indicator on the expected tendering date of the project. So from
the data collected I can determine an increased price on approximately 1.99% a year this means that
from the latest known BPI until the tendering date of the project we have an increased price on
3.98%. Witch also is shown on the graph below.
194.24
198.12
202.06
206.07
185
190
195
200
205
210
2012 2013 2014 2015
BP
I
Year
BPI forecast
BPI forecast
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1.1 Sketch Design Alternative One
Exterior wall
Alternative one is a 125mm thick tilt-up concrete wall panels in 30 MPa concrete, fixed in position,
with a white cement and aggregate finish. Seen from an aesthetic point of view this creates a
simple, calm skin of the building.
The concrete elements comes in panels of approximately 25.0 square meter. All connections joints
and sealants fire rated due to safety reasons.
Insulated on the inside with glass wool batts vertically fixed R 2.5 with the ability to adjust down to
rating R 2.0 the insulation is fixed between wooden studs that forms the inside of the wall. And is
finished with 2 x 13 mm plasterboard rendered and painted with two coats of white semi-gloss
acrylic paint
Windows
At level one there will be windows of clear anodised aluminium shop fronts standard selection
curtain wall glazed with 6mm toughened safety glass.
Between level 2 and 7 the windows will be an aluminium curtain wall, single glazed fixed light
Roof
The roof construction will be a steel framed roof construction consisting of steel work in roof.
Containing trusses/beams up to 15m clear span, steel purlins and insulation in glass wool battens on
mesh, the roof is finished with aluminium ripped decking. The ceiling consist of a suspended
ceiling with acoustic plaster tiles in pre-finished two-way exposed steel suspension system 600x600
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1.2 Sketch Design Alternative two
Exterior wall
The exterior wall is built up with a standard clay brick wall laid in stretcher bond with 270mm
cavity between the two 110 mm skins of brick. The cavity is insulated with 100 mm glass wool
battens R 2.5 witch is the maximum of the recommended by different construction sources, this
allows the client to use R 2.0 if the price needs further adjustment. The insulation is vertically fixed
with insulation plugs of aluminium.
The inside of the wall is rendered with Acratex 1 mm / 2 mm white wash finish witch create a nice
and atheistic beautiful interior surface to give the office a bit of character
Windows
At level one I selected clear anodised aluminium shop front standard selection curtain wall. Glazed
with 6 mm toughened safety glass to prevent theft. At level two to level 7 there will be clear
anodised aluminium framing curtain wall with clear float windows in double glazing. This is due to
the hot summer days where temperatures easily reach 40 degrees +
Roof
The roof on this alterative is a built up roof construction consisting of
Suspended slabs N.E. 150mm thick MPa 25
2 x 50 mm thick Class VH expanded polystyrene prefabricating forgoing to falls against the drain.
Bitumen waterproof membrane, Single layer polyester reinforced app modified bitumen lining 4
mm thick, with add on with bitumen SBS modified waterproof membrane 150mm high skirting
including aluminium trimming.
The ceiling will consist of a normal suspended ceiling with Acoustic plaster tiles in pre-finished
two-way exposed steel suspension system 600 x 600
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1.3 Elemental cost alternative one
Source:
All prices has been collected from Rawlinson’s 34th edition 2014. The location index is collected
from VIC Commercial OCT/NOV/DEC 2014
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1.4 Elemental cost alternative two
Source:
All prices has been collected from Rawlinson’s 34th edition 2014. The location index is collected
from VIC Commercial OCT/NOV/DEC 2014
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Comparing chart
Recommendations
Alternative one witch consist of the tilt up concrete panels and the roof construction of steel is the
more durable of the two options, it is also the most price efficient and time efficient due to its better
and easier build ability.
However there are down sides to alternative 1, from an aesthetic point of view would alternative 2
be more valuable due to the traditional masonry walls and the roof construction and windows. The
walls of alternative 2 is wider and has a better u-value due to the thick brick walls. The same can be
said about the windows, the double glazing will make the building more sustainable and
environmental friendly since there would be a decrease in the use of electricity to heat up, or cool
down the building. The roof solution in alternative 2 is also the better of the two. When dealing
with steel in roof construction as in alternative 1 you have a risk on condensation, this must be
avoided at all cost. My recommendation would therefore end up being alternative 2
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2. Part II: Life Cycle Costing
My client has proposing to build a new office block and asked for my advice on the curtain wall of
the office they should choose. Assuming the interest rate is 3% per annum compound and product
life of a curtain wall is 12 years: I will compare the life cycle cost on option A and B
2.1 Option A
2.2 Option B
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In this case we assume the rate of interest is 6% per annum compound and product life of curtain
wall is still 12 years: I will compare the life cycle cost on option A and B
2.3 Option A
2.4 Option B
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Recommendation 3%
Due to the higher refurbishment and maintenance cost of option B the lifecycle cost exceeds the
cost of option A. the interest of 3% is very low and it is therefore highly recommended to pay more
in the capital cost and get the cheapest outcome in the long run. Therefore I recommend option A as
the cheapest option.
Recommendation 6%
In this case where we deal with an interest rate of 6 % the numbers turn out different even though
we have a higher refurbishment and maintenance cost in option b than in option a, it would still be
the better solution to choose option b this is due to the discount rate that will “discount” the costs of
refurbishment and maintenance so much over time that it would be cheaper to go with alternative B.
I therefore recommend option B as the cheapest outcome in this scenario
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Calculations
Finding the area of the floor plates
12m
80m
GFA = 12 * 80 = 960 m2
The floor to floor height is initially determined at 4.00 meters. Throughout preliminary elevations in
the scheme shows the following:
Floor to ceiling height windows
The level one will contain the offices / showrooms and will have 75 % of the wall glazed
Level 2 to 7 show that 75 % of the total wall area is solid
How much is 75% of level one?
Level one envelope measure = 80 + 80 + 12 + 12 = 184 * 4 = 736 m2
75 % of level one glazed = 736 * 75 / 100 = 552 m2
Remaining 25 % solid = 736 – 552 = 184 m2
How much is 75% of level 2 to 7?
Level 2 to 7 shows 75 % of the total wall area is solid
Envelope measure = 184 * 4 = 736 * 6 = 4416 m2
75 % = 4416 * 75 / 100 = 3312 m2
25 % = 4416 * 25 / 100 = 1104 m2
Total wall = 184 + 3312 = 3496 m2
Total glass = 1104 + 552 = 1656 m2
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Bpi adjustment
How to calculate the bpi adjustment
198.12 – 194.24 = 3.88 * 100 / 194.24 = 1.99752%
198.12 * 1.99 / 100 = 3.9425
Bpi 2014 = 198.12 + 3.94 = 202.06
202.06 – 198.12 = 3.94*100/198.12=1.98869%
202.06*1.99/100= 4.02099
Bpi 2015 = 202.06 + 4.02099 = 206.07
Location index
Since we are building in Geelong CBD the price would be different from the once we got in
Rawlinson’s witch is from Melbourne. So to find the correct price I have found the location index
of Geelong in VIC commercial from 2014. Price index Geelong = 1.005
Melbourne price 1.822.775, 76 *1.005 = Geelong price = 1.831.889, 639
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Discounting
1.0 _
(1+R)n = X
3%
1.0 _
(1+0.03)1 = 0.97087
To get the following years you substitute the power with the year number you are trying to find the
answer for
6 %
1.0 _
(1+0.06)1 = 0.94339
Again here to get the following years you again substitute the power with the year number you are
trying to find the answer for