Kaye Alexander looks at advanced contractual and modelling techniques on an HOK office refurb
The £6 million remodelling of Autodesk’s gallery and offices at the software company’s San Francisco base – One Market Street – is HOK’s first completed project using its new Integrated Project Design (IPD) contract. Underpinning the concept of IPD is the use of Business Information Modelling (BIM) and the incentive of shared profit.
Usually, the parties involved in an IPD contract comprise the architect, contractor and client. ‘On this project, the architect’s role in designing the office and gallery space/customer briefing centre was divided between HOK and Seattle and San Francisco-based Anderson Anderson Architecture, so a four-way variant was drawn up,’ explains Archie Stephens, HOK vice-president.
IPD aims to achieve what the contract terms ‘mutual success’, where each party recognizes that its opportunity to succeed on the project is tied to the performance of the others. ‘The parties will,’ the contract states, ‘within the limits of their professional expertise and abilities, work together in a spirit of cooperation, collaboration and mutual respect.’ The budget for the project is structured in three ‘layers’: a pre-agreed direct expense element for project costs (design, construction and legal); a contingency layer for unforeseeable events; and an Incentive Compensation Layer (ICL). For Autodesk, the ICL was structured around the following principles:
• If the project costs come in under-budget, 50 per cent of the saving is added to the ICL
• If the project is over-budget, the excess comes out of the ICL until it is exhausted
• If the project is within schedule, £4,500 for each day won is added to the ICL
• If the project runs over schedule, £1,500 a day is deducted from the ICL.
These bonuses and penalties vary from project to project. Profit on the Autodesk contract was also subject to the team achieving project design targets for quality, innovation and sustainability (part of the brief stated that the building should achieve a LEED Platinum rating). These targets were set and assessed by an independent third party and the ICL could be adjusted by plus or minus 20 per cent accordingly.
Project management and implementation teams were set up, consisting of one member from each firm. All decisions had to be unanimous and there was no litigation clause in the contract.
‘A typical construction contract for a project like this would be at least two-and-a-half inches thick; ours was only half an inch thick, with single-sided printing,’ says Sam Sparta, director of HOK buildingSMART.
‘By defining the project clearly from the beginning, the client has little wriggle-room,’ explains Mark Flax, HOK director of the San Francisco interiors group. ‘But this means that there are fewer construction change orders.’
The project was an atypical implementation of IPD, because the decision to use the contract form was made late in the process and the budget that had already been set had to be increased. It was decided that no incentive compensation would be paid out for beating the budget or schedule, so all profit was based on achieving the design targets.
The IPD contract form is structured to take advantage of the interdisciplinary practice centred around BIM. The use of BIM has been mandatory for new projects at HOK since January 2006. HOK uses Autodesk Revit to manage the data. For the One Market Street job, the contractor, DPR Construction, had equal ownership and management responsibility for the BIM model alongside HOK and Anderson Anderson. DPR Construction had a BIM team working on site throughout the design and construction process and collaborated with the architect to import the Revit architecture model plus 28 additional system design models into Autodesk Navisworks, to perform clash detection and full co-ordination of all construction phases and details. A large-screen monitor and smart board were installed on the project site and used as a focus for design and construction discussion, detailing, and revision. This meant that accurate information was available to subcontractors for off-site fabrication, and the model could be queried for immediate availability of dimensions, details, and 3D imaging of project details that were not clearly available in the print documents.
All design targets were met, so, at the end of the project, an ICL pool of £467,000 was available, which was split between the parties according to their contribution: HOK (11 per cent), Anderson Anderson (23 per cent) and contractor DPR (66 per cent).
BIM proved especially useful in the design of the building’s ceiling projectors and mechanical and electrical infrastructure. See pages 34 and 36 for a study of these elements.
Problem How to install the gallery’s ceiling projectors and manufacture the stretched fabric ceiling boxes accurately off-site, so that the projected images were correctly positioned, without the need for adjustment once fitted.
Solution By using BIM, the projected light paths from the ceiling projectors in relation to the ceiling boxes could be verified in the model before being made and installed. Some of the ceiling boxes required precisely located cut-outs in their sides to allow the projected image to display correctly. The BIM model helped to determine the exact sizes and locations of the cut-outs prior to fabrication of the boxes.
Problem In order to meet sustainability targets, the team wanted to re-use as much of the existing mechanical, electrical, plumbing and fire protection systems as possible. In order to do this, while including as much prefabrication as possible, an accurate virtual representation of these systems was required for the team to evaluate what could be re-used and to ensure that newly prefabricated elements aligned. The architectural and structural ‘as built’ plans were inaccurate, and no equivalent servicing drawings existed. Accuracy of information was especially important, but difficult to achieve, because the existing space lies within a complex of three conjoined buildings – one of them on the National Register of Historic Places – owned and managed by two different firms, all of which contributed to the potential for confusion and diplomatic complications.
Solution Given the project constraints, 3D laser scanning was decided upon. DPR partnered with BIM specialist Optira to produce a laser point cloud, which was accurate to 0.2mm. An ‘as built’ model was created from this and imported into the BIM model to finalise the design documentation. It was also distributed to the appropriate subcontractors.
Tender date November 2007
Start on site February 2008
Completion date August 2008
Form of contract IPD
Total cost £6 million
Cost per m2£1,560
Office architect HOK
Gallery architect Anderson Anderson Architecture
Main contractor DPR Construction
Structural engineer Tipping Mar
Mechanical engineer ACCO Engineering Systems