The theme of this year’s Glass Supper is Firmitas, Utilitas, Venustas (Firmness, Commodity, Delight) from Vetruvius’ elements of architecture. The theme provides an excellent opportunity to reflect on the importance of the building envelope as it combines functional requirements with performance and aesthetics. The strap line of the event is: Where will the architectural glass industry be in 100 years time? In times of economic and environmental challenges it is quite appropriate to consider how Architecture will undergo changes and how these changes will impact on the construction industry. It is both interesting and relevant to consider how new drivers including legislation will bring about changes at different scales – from urban design to material science. At the Glass Supper we will be focusing principally on architecture and glass, current challenges and future opportunities. High performance buildings with low environmental impact require collaboration across design disciplines and supply chain. The aim is to create durable and resource-efficient buildings of high architectural standards – More with Less is the overarching ambition. The devil is in the detail and so besides much-needed technological progress and a deeper understanding of fundamentals it is of paramount importance that designers are empowered to adequately consider high performance solutions at the early project stages. The designers will need new skills in the future and they will need access to the right information from suppliers and contractors. While the need for interdisciplinary working and integrated design has been acknowledged for years, legislation is likely to require closer links between designers and supplier to meet the stricter regulations of the future. It is well-known that building regulations will never represent cutting edge solutions – That is not the role of legislation. The environmental policies on the other hand will drive change and we all need to reflect on our own role in a changing set of circumstances. Thought-leaders set new standards and – by doing so – aim to secure a place in the future marketplace for high performance building solutions. Innovate or stick with business as usual? Lead or follow?
HIGH PERFORMANCE AND LOW IMPACT
One definition of a successful building project is “a project that will meet or exceed the Client’s expectations, be delivered on time and on budget”. How do you then define high performance? Well, it depends on the point of view. The term high performance building will typically cover aspects of durability, energy savings, occupant comfort, and aesthetics. The specific context and the Client’s requirement will determine which of these aspects are of high priority and which are negotiable. Increasingly, low environmental impact is seen as high performance. By some forward-looking designers it is even seen as a given and not really the subject of much discussion.
Visionary clients and developers – with the help of their designers – target high performance because of its impact on corporate image, staff retention, and potential savings on operational costs. Comparatively less visionary clients and developers will follow suit as legislation tightens the requirements. Environmental rating schemes are meant to affect the way projects are delivered, forcing project teams to work together more closely and assess options early on in the project.
Some clients and project teams aim beyond code, and target environmental ratings which are not strictly required by legislation. However, ambitious targets can be hard to justify unless the design team can provide evidence and demonstrate that the cost premium is not excessive. The onus is therefore on the design team – in close collaboration with contractors and suppliers – to develop and communicate solutions, which offer design advantages without incurring excessive or even prohibitive cost premiums. In a sector where the focus traditionally is on first costs a paradigm shift is required if due credit is to be given to high performance.
Add to the perceived cost of high performance the aesthetics and the fairly delicate discussion about architectural quality. This is the Delight element - Venustas - which is both subjective and often difficult to define as it encompasses qualities such as light and shadow, transparency and reflection, colour, texture, materiality and form language.
TRANSPARENCY AND BEYOND
Over the past decades, highly transparent facades have become almost the default expectation in high end commercial developments. For these systems to perform to the ever stricter energy performance requirements they are often realised as so-called double skin facades, which is an effective way of offering variable performance and a high degree of transparency when solar shading is not required. The variability of the facade including the shading system in effect becomes an important part of the architectural expression. Thus it is possible to offer high performance though dynamic systems. The premium for these solutions is more often than not justified in an architectural discussion where transparency is a key performance parameter or a fundamental requirement.
Progress is being made in the field of switchable glazing as a means of controlling transmission of solar radiation within the glass itself. Liquid crystal display technology is being used in privacy applications and the potential in daylighting application is being explored. Also here, Dow Corning is actively pushing the envelope, introducing silicon science in this new field of high performance architectural applications.
The pressure to reduce carbon-intensive cooling in buildings has led to a reduction in the ‘default’ fully glazed facade. Architects are finding new forms of expression, where the non-transparent (non-vision) part of the building envelope gains prominence as an alternative aesthetic for energy efficient buildings. In this context there is growing interest in materials and geometry as ways of breaking up the building elevations and moving away from the now conventional spandrel strip and floor-to-ceiling vision glass. We are witnessing a trend where the building envelope becomes colourful and in some instances even playful – again adding an element of delight.
Reducing the vision area is obviously a very efficient way of dealing with solar gains and the resulting, carbon-intensive cooling. And obviously the impact on daylight availability should always be considered to provide occupant visual comfort and reduction of energy used for electrical lighting. As the vision area reduces and the architectural language starts to involve potentially complex detailing of the insulated parts of the building envelope, the thermal performance of the facade depends closely on how the insulated areas are detailed and in curtain walling the effect framing needs to be taken carefully into account.
The thermal performance of curtain walling needs to be assessed for the whole assembly, including vision area glazing, insulated areas, and – crucially – the framing. Projects with relatively limited vision area percentages and complex detailing of the opaque, non-vision areas will increasingly require high performance thermal insulation to meet performance requirements given common space constraints. One such novel solution utilises vacuum insulation panels (VIP) as a means of offering the highest thermal performance within a given available thickness or – interestingly – compacting the thickness of curtain walling for a given performance requirement. Dow Corning’s architectural insulation modules are based on well-known IGU technology, enhancing the performance of non-vision areas through integration of fumed silica core VIP solutions.
THE SPECIFIER AND THE SUPPLIER
In a sector where there is no ‘one size fits all’ and virtually every project is different there is inevitably an element of risk management, which stands in the way of project-specific optimisation. In a time where the economic climate and the environmental agenda present challenges, there is an increasing focus on integrated project delivery. Important design decisions are made at the outset of projects with subsequent changes being potentially both complex and costly. Therefore, as environmental ratings creep up the agenda and priority is given to early stage optioneering, the relationship between the design team – or the Specifiers – and the suppliers is of paramount importance. Why? - Because the design team can only ever develop successful solutions if they have access to detailed information on relevant options. The suppliers in turn need to be able to articulate in an appropriate and relevant format the characteristics of their offering, including performance metrics and design constraints. This working relationship will eventually lead to the development of novel solutions based on feedback from cutting edge project work and the experience of highly skilled people.
COST, VALUE, AND WORTH (GREEN IS THE COLOUR ...)
High performance is desirable for an owner-occupier due to long term benefits. To a commercial developer, however, high performance is typically more interesting in terms of marketability as environmental performance becomes a central commercial parameter in negotiations. Environmental ratings are increasingly seen as a differentiator in the commercial market, with prospective tenants comparing the ratings of property on offer – all other things equal. It is likely that there will come a time where property cannot be let or sold if its energy performance certification falls short of certain thresholds stipulated by regulation. In such situations building energy performance translates into capital value as upgrades will have to be factored into the negotiation. This aspect will inevitably affect decision making which, incidentally, is the purpose of the policy directives. And then there is the question of planning permission, which can depend on convincing evidence of environmentally conscious design principles. This can be a key element in terms of technical and commercial risk as it can be costly and time consuming if planning against expectation is not granted and redesign turns out to be necessary.
Then there is another aspect of Design, which pertains to the high end of the property market, where aesthetics and choice of materials impact on market value. The client brief will set out the requirements and the designer will be chosen with due regard to reputation and ability to deliver such high end projects. In these situations, the designers ability to consider appropriate technical solutions early on is likely to prove critical to proving the feasibility and avoid costly abortive work.
In addition to the crucial durability of solutions, a key component of environmental performance is the lasting qualities of buildings. A quality building is more likely to be looked after by its owners and users and it is more likely to be adapted to changing requirements over time. The quality comes through in carefully crafted fabric and detailing as well as the nature of the space within and around the building. Future proofing buildings through high performance will inevitably add to their worth and this should ultimately translate into commercial value.
It is not all doom and gloom as progress is being made on many fronts including materials science, building envelope technology, and design tools. High performance building solutions will require new solutions bridging sectors perhaps not conventionally or traditionally associated with construction. The ability to modify the properties of construction materials will cater for enhanced performance and durability, provided that the materials are used appropriately. Outside of sealants and structural glazing, silicon science is a field which is not widely considered part of the high performance building arena. Well, that may change as Dow Corning continues to collaborate in pursuit of high performance solutions with low environmental impact on the route to the net zero buildings of the future.