W I N T E C H. Wintech Group. Façade performance. Chris Macey. MBA, FSFE. The Truth, Lies and Psi Values.

Transcription

1 W I N T E C H Wintech Group Façade performance The Truth, Lies and Psi Values. Chris Macey. MBA, FSFE Wintech Group Managing Director Wintech Façade Engineering. Past Chair of the Society of facade Engineering (CIBSE)

2 W I N T E C H Building Façades are: Up to 40% of building construction costs. Are the most visually important element. The primary environmental modifier The element which has the greatest level of historic problems.

3 W I N T E C H Façade Engineers? Who are the key professional team members on a major project? What makes a Façade Engineer, who are we relying on now. The need for proper professional training and accreditation of players in the façade consultancy industry. The Society of Façade engineers.

4 W I N T E C H Who are the Wintech Group? Facade Engineering. Design Testing Consultancy

5 W I N T E C H Design Petronas Towers Kuala Lumpur, Malaysia Architect: Cesar Pelli

6 Spin off benefit of New Technologies? W I N T E C H

7 W I N T E C H Testing European Notified Body UKAS Accredited. CE Marking Facility. ATTMA Member

8 Consultancy W I N T E C H New Build Services. Strategic Façade development. Options analysis. Façade performance analysis. Cost prediction. Specification design. Value engineering. Tender Analysis. Design Audits. Test sample witness. Site inspections. Existing Building Services. Building failure investigations. Procurement inspections. Risk and cost assessments. Remedial design schemes and project management. Expert witness.

9 W I N T E C H Recent and Current projects Manchester Civil Justice. Client: Lendlease Architect: Denton Corker Marshall

10 W I N T E C H The Energy Balance Plant capacity (Services Design) Façade Performance (Facade Design) Internal lighting Solar Overheating Air Egress. Cooling Load Heating load Natural lighting Solar Shading Air Tightness. Photo Voltaic s Insulation

11 W I N T E C H What performance attributes are we looking to improve. The performance factors of facades that have an affect on the energy consumption of a building are : U values: energy lost or gained as a result of conduction. Solar shading: long wave solar radiation solar heat gain in a building. Uncontrolled air permeability: air leakage into or out of a building. Light transmission, Internal daylight factors in the building. Longevity: Performance for the life of the development.

12 W I N T E C H From a sustainability perspective: Energy performance of buildings comes in three categories, only one is regulated. These are: 1. The in use energy performance of the building and it s contribution to whole building energy use. 2. Embodied Energy in the manufacture and installation of the facade. 3. Life cycle cost. 4. Recycling benefits

13 W I N T E C H For Example. It takes 2.5 KWh to produce 1 kg of glass. You may have to process over 5 tons of Bauxite to get just one tone of aluminium. It takes 15 KWh to produce just one Kilo of Aluminium in the conversion process. However it takes just 5% of this initial energy figure to recycle the material into another form. This represents a step change like a car going from 35 to 700 miles per gallon. (Professor Michael Stacey) 75% of all aluminium produced since 1888 is still in use today (CAB)

14 Façade Performance and Dew Points W I N T E C H

15 Façade Performance and Dew Points W I N T E C H

16 W I N T E C H Façade Performance and Dew Points There are two issues: The prevention of condensation on the inside of buildings. This is currently dictated by BRE IP 1/06 The assessment used assumes fixed state environments. Written specifically about building with absorbent surfaces and a fixed state, the standard is often applied to light weight no absorbent facades such as curtainwall and cladding. Thermal mass isn't taken into account. We would recommend that CWCT recommendations which are less onerous and take into account the transient nature. The lesser know issue of interstitial condensation. No standards exist for this at all.

17 Façade Performance and Dew Points in light weight constructions W I N T E C H

18 Façade Performance and Dew Points W I N T E C H

19 Façade Performance and Dew Points in light weight constructions W I N T E C H

20 Thermal Bridges and Psi Values. W I N T E C H

21 Why is it worth talking about thermal bridges? Government challenge: Reduce the operational energy consumption of building services by increasingly improving the Thermal Performance of Building Envelopes Growing demand in the UK market for lightweight and highly glazed facades Need to deliver cost effective high thermal performance facades Tighter U value requirements mean increasing significance of thermal bridges Increase focus on design details and solutions that help to prevent the occurrence of thermal bridges Systems able to provide solution to enhance the thermal insulation of the building fabric difficult to avoid thermal heat losses due to the nature of the system components, and the complexity of the architectural design Paola Miranda Modina MSc Façade Engineering

22 W I N T E C H Regulatory Compliance. Driven by the increasing need for enhanced façade performance We are not achieving regulatory compliance today!

23 W I N T E C H

24 Different types of thermal bridges in building envelopes In the framework of the UK Building Regulations, they are distinguished in: Repeating thermal bridges Generally in a regular pattern and uniformly distributed over an area of the thermal envelope Non Repeating thermal bridges Occurring at construction junctions due to discontinuity in the thermal envelope or geometrical configurations References: Thermal bridges may occur at various locations of the building envelope, where there are elements or parts of the construction that are more thermally conductive than the rest of the façade; or there are specific geometrical conditions (BRE, 2007) U value calculations Ψ value calculations Thermal bridges result in additional heat loss from the building envelope and potential localized cold spots leading to condensation build up or mould growth (ASIEPI, 2010) Paola Miranda Modina MSc Façade Engineering

25 Current Practice, limitations and challenges UK Building Regulations Standard methodology for assessing non repeating thermal bridges References: OPT a. Use of a single, onerous, default figure added into the total transmittance of the building envelope OPT b. Use of default values for each junction based on approved details OPT c. Use of user supplied values for each junction based on design specific calculations The design needs to improve significantly elsewhere to meet the energy requirements No reference is made for lightweight construction details Added complexity Paola Miranda Modina MSc Façade Engineering

26 Qualitative survey on the most recurring lightweight façade systems Paola Miranda Modina MSc Façade Engineering

27 By Analysis W I N T E C H

28 Consider the design complexity Due to the uniqueness and the complexity of each architectural detail, the same façade junction can result in several variations Thermal Resistivity of the internal insulation Internal lining abutment location/potential internal insulation Thermal continuity at interfaces Thermal Resistivity of the external insulation Ψ? Location of the window jamb Location and size of the cavity barrier RAINSCREEN TO WINDOW JAMB

29 Step 3: Provide performance consistency 3) Maximise external insulation relative to internal insulation 1) Thermal continuity at interfaces 2) Window frame aligned to the thermal insulation Ψ= W/mK RAINSCREEN TO WINDOW JAMB

30 Step 4: Accurate and simplified method of evaluation Parametric analysis process E.g. Variable = Window location Ψ= 0.07 W/mK Ψ= 0.01 W/mK Ψ= 0.01 W/mK Ψ= 0.02 W/mK R ins= 5.00 m2k/w 75mm 0mm +50mm +100mm

31 By Analysis W I N T E C H

32 Design Calculation Comparison W I N T E C H

33 Design Calculation Comparison W I N T E C H

34 Jewish Community Building W I N T E C H

35 A Retrospective Assessment. W I N T E C H

36 W I N T E C H The Results. DETAIL Window jamb to rainscreen Type 1 Type 2 PSI VALUE (W/mK) Calculated Accredited Detail Default Type Window jamb to precast concrete cladding Window jamb to brickwork Window cill to brickwork Door threshold to insulated terrace Window head to brickwork Door head to insulated balcony Brickwork to rainscreen Brickwork to precast ?? (not envisaged by SAP)?? (not envisaged by SAP) Rainscreen to partywall External corner brickwork

37 W I N T E C H So what s the answer? We need to make sure that building designs take cognisance of what's actually achievable. Facade performances are not specified to be aspirational. We need to understand how performance is achieved. We cant always rely on what the team are told by bidding contractors. Engineering services and facade engineering are inextricably linked.

38 W I N T E C H We now need to: Evaluating Thermal Bridging using Façade Engineers. Specifying in the context of the Architectural design. Architects should design in the context of what is needed. Making sure contractors deliver and install what's actually needed and not what they can get away with Changing the process and the culture in which we specify, design manufacture and build our buildings. Take the benefit of professionals that don't have an interest in the commercial aspects of specific product use.

39 How to move things forward? Step 4: Provide an accurate and simplified method of evaluation Step 3: Provide performance consistency Step 2: Consider the design complexity Step 1: Fill the gap Identify the typical thermal bridges in facades Provide practical information about the thermal behaviour of different detail configurations to inform the design. Provide validated thermal analyses for different configurations Parametric or Standard analysis of selected details varying the main design parameters TIME EVALUATION

40 New Paradigm Start Structural Engineer Architect Facade Engineer Services Engineer Strategic PROJECT DURATION Tactical Design Delivery Completion

41 Thanks for your attention