Tag: Volumetric

The term ‘Modern Methods of Construction’ (MMC)  embraces a range of technologies involving various forms  of prefabrication and off-site assembly.

MMC is increasingly regarded as a realistic means of  improving quality, reducing time spent on-site, improving  on-site safety and addressing skills shortages in the  construction of UK housing.

The variety of systems now available potentially allows the  designer enough choice to sidestep problems deriving  from constraints posed by the use of any one method.  MMC systems, from closed-panel timber framed  systems to bathroom pods are a palette from which  designers can make choices. They are not necessarily  stand-alone solutions that anticipate all the needs of  an individual site and can be mixed and matched  as appropriate.

These limitations are not obstacles to achieving the good design in MMC-based schemes, but may hinder  the incorporation of more complex and innovative  types of MMC from which greater overall benefits  may be obtained  which  are considered under the  following headings:

1. COST UNCERTAINTY

There is no doubt that, given products of comparable  performance the key issue in purchases of MMC construction  systems is the price. At present not enough is known  about the potential costs of using volumetric and  closed panel systems to enable confident specification  at an early date. This inhibits designers from exploring  the full potential of MMC systems. This is particularly true of the less repetitive,  small, one-off scheme, where a smaller margin  of benefits is gained from using MMC. The principal  barrier to the uptake of MMC, therefore, seems  to be the perception of cost uncertainty with respect to using more complex systems.  Without doing substantial project-specific research,  consultants and their clients simply do not know with  enough degree of certainty how much the volumetric or  closed panel systems are likely to cost, and what  would be the savings to overall project costs produced  by potential speed gains to offset against increased  capital expenditure.

This is due to the complexity of assessing the ratio of  cost of repetitive elements where pricing is relatively  straightforward to the cost of adjusting elements or  building in another method for the abnormal condition.  Decisions to use innovative systems are likely to be  made once designs are well progressed to enable  teams to be more certain of costs. This can increase  the potential for change or result in design compromise  as the designer attempts to incorporate the specific  limitations of a particular system in their design.

In an attempt to improve this situation, the MMC consultant and or clients  could  pull together a  directory of MMC  expanded to include cost comparison data. The huge  range of variables involved inevitably makes this  difficult, but a database of current construction cost  information  would be an  invaluable resource.

2. PLANNING PROCESS AND EARLY COMMITMENT  TO A SYSTEM

The time it can take to obtain planning permission has  obvious implications both for project cost but also, in  some circumstances, for architectural  design innovation.

Most of the more complex types of MMC have an  impact on dimensioning, the choice of external finish  and detailing may have some effect on the buildings  mass. Therefore,  the construction system should be  chosen prior to a planning application to avoid  abortive work, redesign or amendment, or even  resubmission for planning permission.

However,  developers  whose money is at risk, frequently hold  off deciding on the construction technique until the last  practicable moment, in order to get any advantage from  fluctuations in material or component pricing.

Given the potential for lengthy duration of planning  applications, this means that there is little incentive to  prepare initial designs for planning with a prior decision  to incorporate MMC firmly embedded. In cases where  the developer has a financial or business link with the  supplier, this is less likely to be the case. As the majority  of commercial or  residential developments involve some kind of arrangement with a developer, agreement on construction systems is often left to the stage after planning.

3. TIME INVESTMENT

Another very significant factor is the time investment required at  the early stages of projects. This is needed to develop the design when the project is still at risk. There is a  direct relationship between the scale and complexity of  MMC component and the amount of time required to  develop a design at an early stage.

The introduction of advanced or complex MMC  techniques into the design process is potentially costly  to the design team. A significant amount of research is  needed to explore alternative systems, to obtain  verification of suppliers’   credentials, investigate  mortgage and insurance issues, visit previous sites,  talk to system suppliers, obtain technical performance  guidelines, understand junctions and interfaces, coordinate  other consultants, obtain building control input  and so on.

For a consultant, the only way of investing in this  research is either through timely payment of increased  fees by a visionary understanding client or through the anticipation of increased future productivity through repetition when a  project is phased, or large enough, or likely to be  followed by another similar project.

The potential of learning a system and then being able  to repeat lessons learned efficiently is a powerful  incentive for both client and consultant. By contrast, HTA’ s project at Basingstoke is an example  of a phased project with a three to four-year duration allowed the design team to repeat  various elements of the design, and the manufacturer to  develop improved solutions to technical and supply  problems.

4. INSUFFICIENT COMMUNICATION

Improved dialogue at the outset of the  project is  vital if design quality is to be  maximised. Constraints and opportunities implicit within  a particular system are more easily incorporated into  design if partners communicate pre-planning.  Increased early communication can be fostered through  improved long-term partnering relationships.

Clients  should also partner with a range of suppliers and  architects so that choice and flexibility is not restricted.

5. INEXPERIENCE

Generally, the inexperienced client or design team will  have to do more research, with the result  that there is likely to be significant design development  without a specific system being incorporated.

This is a  disincentive to using a more complex system involving a  higher proportion of MMC, where early decision making  and knowledge of a system’ s capabilities have a decisive influence on the nature of the architecture.  However,  encouraging the take up  of MMC through the use of a dedicated funding mechanism may  assist clients  in  finding time for  research into suitable MMC techniques.

6. SUPPLIER’S ROLE

Site capacity  studies and early stage pre-planning design studies  could be undertaken directly by system suppliers  on behalf of clients, cutting out the usual procedure  of commissioning design work by independent  consultants.

7. ASSUMPTIONS

There are a  number of assumptions that  are generally held about certain types of MMC that may  have been valid at one time but are no longer true today.  There is a need for reliable and up to date information  comparing system criteria, performance data, timescales, lead in times, capacity, construction time,  sequencing issues, limitations, and benefits.

Therefore  it would be helpful if a forum  for discussion and experience exchange was set up.

8. DEMONSTRATING THE BENEFITS OF MMC

There is still a large amount of skepticism about the  need to go very far down the line with MMC. This is  reflected in the acceptance of the desirability of  maintaining or indeed enhancing the pool of traditional  craft skills throughout the UK.

A balanced view is that there is a demonstrable need  for the wider use of MMC which is recognized by both  industry and government.  The best way for clients  and the public generally to  become more confident and knowledgeable about the  quality of design achievable through MMC is to see it  demonstrated.

9. FINANCIAL INCENTIVES

There is no doubt that spreading the burden of  investment through the life of a project helps to ensure  a higher standard of specification and hence quality. In  the Netherlands, a ‘ Green Financing’   system has been  developed by the Dutch government that provides  favorable loan finance when certain sustainable  standards are reached. In the UK, the Gallions HA  has  pioneered  a study of this, based on a scheme in  Thamesmead, ‘ the Ecopark project’.