The debate about what is a high performance façade, or how does one define a high performance façade could almost be compared to a debate about Politics. Everyone has their opinion, as is their right. It’s doubtful you will end that debate with a different opinion than the one you had when you started, hopefully you will have learned something useful, and hopefully you would have been given food for thought, perhaps even something to add to your already informed ideals. However, I will move from the general on to the particular and focus on one aspect of high performance which I believe will greatly benefit us all – Collaboration.
But this may not resolve all the issues of the interface. For this core interface to be effective:
• the design team needs to consider construction and buildability from the outset
• the contractor has to understand the rationale behind the design concept
• ways of communicating project risks must be agreed so that they can be understood and managed
• means of progressing cost information agreed
• methods of harnessing design skills of specialist suppliers and subcontractors developed, and this is particularly the case with the design of high performance facades.
I would suggest that the biggest conundrum in the construction industry is the interface between the design team and the delivery teams, and how to make this core relationship work more effectively. One way of breaking through the cultural barrier is to harness collaborative project teams where all members of the team work together to achieve the client’s goals and objectives…to balance the quality, cost, and time variables. To achieve effective collaboration, the client may select a procurement route that harnesses early contractor engagement.
Hodder + Partners most recently completed project for Student Castle in Manchester comprises 520 study bedrooms over 37 storeys. Delivering cost effective student accommodation can be challenging, more so at height. Shepherd Construction was engaged during pre-planning to bring their knowledge of programming and delivery processes to bear on the emerging proposals. Key packages, such as the external façade, were market tested in advance of making the planning application in order to bring some certainty, and de-risk to the procurement process. Commencement on site was achieved within a month of receiving consent, and the £30m project was delivered on time in 100 weeks.
I would like to speak about the design process, because for me the process needed to achieve a high performance façade, or a building, requires an integrated approach, an approach where teams work together to design an architectural solution that is functional, comfortable, energy-efficient and yes, even beautiful.
I have to confess that this does indeed touch on one aspect of my agenda for the RIBA over the next two years…that of project team collaboration. Despite there being a clear definition of roles and responsibilities, I’m sure we have all experienced buildings being delivered late and over budget, primarily due to a prevailing adversarial environment triggered by the ‘them and us’ attitude, and often fuelled by the practice of lowest cost tendering.
The traditional way of working has altered greatly over the years, as a consequence of changing procurement routes designed to resolve these cost and programme issues, but also in response to the increasing complexity of building technology and specialist subcontractor design.
The RIBA recently published ‘Assembling a Collaborative Project Team’ which builds on the new Plan of Work. It seeks to demonstrate how the best way of assembling a collaborative team is by establishing who is the project team at the outset and by ensuring each party is fully aware of what they need to do, and when, and by agreeing how this will be achieved. (4)
The notion of collaboration has been embedded in my work from my early days in practice when I was at BDP. All of my buildings have been as a result of a close and integrated working relationship, not just with the design team, but with the delivery teams as well.
The UK Government’s strategy for construction ‘Construction 2025’ contains some challenging targets;
• 33% reduction in both initial cost of construction and whole life cost
• 50% reduction in overall time from inception to completion
• 50% reduction in greenhouse gas emissions
• 50% reduction in the trade gap between total exports and imports for construction products and materials
I would suggest that the only way we can remotely meet these targets is by effective collaboration, and of course we now have the tools in Building Information Modelling (BIM). What we now need is a collective approach. Why am I focussing on collaboration you may ask? Well, because I hold a firm view that a high performance façade may only deliver the greatest performance to both clients and occupants when it is considered as part of a fully integrated building design and its systems. Integrated design can very often entail complex systems and require a high degree of technical understanding. All constituent parts have to be considered collectively because the consideration of one at the expense of another can result in the elimination of an idea leading to unbalanced, or even poor building performance. This necessarily involves the whole project team working together with the same goal from the outset of any given project.
A study into ‘High Performance Commercial Building Facades’ conducted in 2002 at the University of California makes reference to the need for fully integrated building design. It suggests that a façade should not be treated solely as a building skin, but as part of a system, a holistic consideration that considers;
• Solar protection and cooling load control, whilst optimising on thermal comfort and daylight.
• Air quality and natural ventilation.
• Operating and life cycle costs by minimising lighting, cooling and heating.
• Quality of internal environments leading to occupant health, comfort and performance.
And of course all of these considerations are essential components in effective sustainable design.
For twenty years Hodder + Partners has been architects to St. Catherine’s College, Oxford. The College was the only new undergraduate college in Oxford in the Twentieth Century. It was commissioned by the great historian and founding Master Lord Alan Bullock, and designed by the distinguished Danish architect, Arne Jacobsen in the early 1960s. It is now one of only eight post-second World War Grade I listed buildings in the UK.
We have extended the College on two occasions; initially in 1995 and more recently in 2006. In the intervening period we have been engaged in conserving Jacobsen’s masterpiece, one project being the replacement of the 3600 windows to the residential blocks in conjunction with Jacobsen’s surviving practice, Dissing and Weitling, and Peerless windows in the US. The originally single-glazed residences suffered terribly from solar gain. Our solution was to introduce thermally-broken, double glazed widows with interstitial solar control blinds behind retained historic fabric.
There is a secondary message here. 80% of our existing building stock will still be in existence in 2050. Delivering a zero-carbon Britain by then will require a massive programme of upgrade and the introduction of high performance facades in existing buildings will be a strong source of work for the industry.
The second phase at St. Catherine’s comprises 132 new study bedrooms, and a new Porters’ Lodge with teaching rooms above. We worked with the structural engineer, Les Postawa of Thornton Tomasetti, and the environmental engineers, Max Fordham.
Solar control to the new naturally ventilated study bedrooms is by way of pre-cast concrete bris soleil. But the Lodge is the outcome of a truly integrated approach to design, good collaboration. The curtain walling system is a proprietary Kawneer PF system, with integrated opening lights. Solar gain to the east, west and south elevations is mitigated by solar shading arrays of Western Red Cedar louvres. Tempered air is admitted at each floor level and exhausted by flues between the teaching rooms and galleries. This is assisted at certain times of the year. The enclosed ‘teaching box’ is of in-situ concrete clad with highly insulated stainless steel panels, its thermal mass and night-time ventilation used to attenuate seasonal extremes in temperature.
What were the lessons we learned from this project?
• All too often ‘first costs’ at the expense of life-cycle costs are the primary consideration and militate against integrated design and the specification of high performance facades. Not willing to invest more at the beginning of a project to realise larger savings later is a poor business strategy. The Fellows at St. Catherine’s College are an informed client in this regard. Aside from which our experience in this instance was that the integrated approach to the design of the façade cost less than an elaborate building skin; the integrated approach to the building design saving on complex mechanical ventilation systems.
• Operating integrated façade and building systems require careful induction for the client. It was necessary for Max Fordham to re-visit post construction as communication of the design intent and commissioning by the delivery teams was not ideal. However, overall operating and maintenance costs are demonstrably lower.
I would like to conclude with a project we designed together with Arup, Corporation Street footbridge in Manchester, which became one symbol of the City’s recovery from the terrorist attack in 1996. On 15 June 1996 a large bomb exploded injuring 220 people and causing immense physical damage to the core of Manchester city centre and its social and economic fabric. The shattered footbridge, which connected two shopping centres across Corporation Street, remains one of the most vivid images. The renewal programme is now complete and in 1997 the competition for a new footbridge was won.
Contextually Corporation Street is canyon like and is a significant, linear north-south route through the City culminating with the civic space of Albert Square. The footbridge takes the form of a hyperbolic paraboloid of revolution and appears as a lightweight glazed membrane stretched across the street. Its transparency is heightened by the arch which permits uninterrupted aspects along the street, and whose symmetry optically redresses the change in level of the boardwalk which threads through from side to side. Outside the membrane are 18 straight 25 mm tension rods and 110 mm circular hollow section compression members which spiral in an alternating clockwise and anti-clockwise direction.
Truncated conical collars anchor the structure to buildings either end and naturally ventilate the bridge. New materials and techniques continue to be developed in the search for even better high performance façade design. Design and procurement is highly technical and complex. My underlying thesis is that this must be a necessarily integrated and collaborative process…a holistic approach to building design right from the outset of a project.
Stephen Hodder President of the Royal Institute of British Architects (RIBA)