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PRACTICAL APPLICATIONS FOR CONSTRUCTION AND THE BUILT ENVIRONMENT


Innovation & Research


Issue No. 64


IN THIS ISSUE Buildings


Vibration tests on floors


Coastal Engineering Beach lowering at seawalls


Construction futures Erabuild


Where next for construction? Design


Reducing air in pipelines


Reducing slip-related accidents Ground engineering


Remediation technology transfer


Highways & Infrastructure New plastic bridge


Affordable infrastructure IT


Information delivery on site Materials


Reducing slip-related accidents


Renewables Wind turbines


Safety Reducing slip-related accidents


Sustainability Erabuild


Where next for construction? Tunnelling


UK tunnel database 6


8 3


5 4 2


8 3


4 6


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3 7


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Concrete towers enable larger turbines5 New plastic bridge


3 6


5 Also at www.innovationandresearchfocus.org.uk


Standard for systemised building envelopes


The use of a performance-based specification is essential when designing and procuring building envelopes. Performance is increasingly complex and has to include thermal, acoustic and lighting performance in addition to weathertightness and air permeability. Performance-based specifications have to be comprehensive and relevant to site and project conditions. Furthermore, building envelopes are becoming more diverse in their construction and there is a trend to mix and match different constructions within one roof or wall.


I


n recognition of these trends the CWCT stan- dards for curtain


walling, ventilated rain- screens and slope glazing have been updated and integrated into a single Standard for systemised building envelopes. The CWCT Standards have been in use for twelve years in some thirty-three countries. They are taken as the basis for the National Building Specification (NBS) and the standards of the National House Building Council


(NHBC). The new CWCT Standard has been writ- ten by CWCT members, drawn from the broad spectrum of the curtain walling industry, under the guidance of its Technical and Standards committees. The docu- ment includes the new BS EN Standards for


dynamic aero engine test, which is the only suitable way for testing any venti- lated rainscreen and the only practical way of test- ing most sealed building envelopes.


Facade watertightness testing: dynamic aero engine method in accordance with CWCT ‘Standard for systemised building envelopes’, courtesy Wintech.


curtain walling and takes account of the changes to the Building Regulations regarding conservation of energy (U-values, air leakage and g-values), sound insulation, fire perfor- mance and access for the disabled. The new BS EN Standards for curtain walling are not appropriate for walls clad with ventilated rainscreens (an increasing proportion of walls) and the new CWCT document fills the gap in the CEN standards. The BS EN Standards include an optional dynamic water test but it cannot be used with curtain walls of complex geometry or with attachments such as brise soleil (a significant majority of custom walls). The CWCT Standard has retained the


www.innovationandresearchfocus.org.uk


The Standard is arranged as separate parts covering: PART 1 – Scope, terminol- ogy, testing and classifi- cation; PART 2 – Loads, fixings and movement; PART 3 – Air, water and wind resistance; PART 4 – Operable com- ponents, additional ele- ments and means of access; PART 5 – Thermal, mois- ture and acoustic perfor- mance; PART 6 – Fire perfor- mance; PART 7 – Robustness, durability, tolerances and workmanship; PART 8 – Testing;


PART 0 – Specifiers’ checklist and certification. There is a complementary document Standard test methods for building envelopes, which describes each test in detail. The new Standard gives a framework for specifying per- formance and gives both mandatory clauses and supplementary advice. The specifiers’ checklist is included to assist the decision-making required to produce a specification that is applicable to a particular location, building and use.


For further information please contact Brenda Apted at CWCT (01225 386541; E-mail cwct@bath.ac.uk).


Innovation & Research Focus Issue 64 FEBRUARY 2006 1 February 2006


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