20th August 2003
Making Green Work
Just how green can you really go? This is a modern dilemma facing the conscientious designer. We are constantly learning about new techniques and new products that can save energy, or reduce resource consumption, but we need to balance our enthusiasm for these innovative technologies with pragmatic realism.
Clients need professional advice, and this means understanding the cost implications of going green, and – perhaps more significantly – the risk implications. The challenge is to ensure that clients have sufficient information to make the right decisions, decisions that are made in the best interests of the project, as well as the environment.
Within the Irish construction market, low-energy and sustainable-driven design is still something of a novelty. In the commissioning of public buildings, the government is increasingly seeking some element of sustainable design, but commercial developers resist such innovative technologies in a relatively volatile marketplace.
The Dublin office of international consulting engineer, Buro Happold, has taken a particular tack on the green debate, and the result has led to a string of sustainable design solutions that, by leading from the front, have impacted directly upon design trends in Ireland. The ‘going green’ approach is based around close collaboration with the client and the architect.
Buro Happold has established a reputation for low-energy design across the globe. The experience gained from designing buildings around the world can be shared and developed. The knowledge gathered to design buildings can be shared, re-applied and refined. This collective knowledge has been driving up the green agenda in the Irish market, but it has not always been easy. Leading from the front with a green agenda has also drawn attention to some of the difficulties that arise when designing truly low-energy buildings that work in a commercial environment.
Some of the first projects that the Buro Happold team designed in Dublin were for local government. The brief from Limerick County Council for their new Civic Offices, was for a naturally-ventilated building which would be well-tempered and have good acoustic properties. Buro Happold worked with the client and Bucholz McEvoy Architects, to develop a shaded atrium solution, which assists in drawing air across the open-plan occupied areas, allowing for good ventilation without undue noise transfer. The Dunshaughlin Civic offices, by Grafton Architects, aimed to be more adventurous with a mixed mode solution adding the benefit of heat reclaim in winter, coupled to a natural ventilation strategy with exposed thermal mass for summer temperature modification. Both these solutions display a modest ‘green’ approach – there are no visible photovoltaic arrays or wind turbines – but, combined with careful attention to orientation and material selection, the resulting designs aims to reduce energy consumption by a significant margin.
When the business software house, SAP, were looking to consolidate their various Dublin offices into a single location for their Software Support Centre, (SSC) they sought a design team sympathetic to their ‘green’ aspirations. An initial feasibility study had identified that fitting out a shell-and-core developed space would be preferable to investing in new-build; SAP wanted their new SSC on-line fast making procuring a new building impossible. A building of 7,000m2, already rising out of the ground within a new technology park eight miles to the west of the city was ear-marked, and a design team assembled to advise on a low-energy fit-out to this speculative office building.
Architects Bucholz McEvoy were faced with an ‘E’ shaped, two-storey building of modest width (13m wide floorplate) that was suited to natural cross-ventilation. However, the building faced south, leaving the three office wings with east-west aspects – and consequently tricky solar gain and glare problems. In addition, the site was an exposed business park, with no shading from adjacent trees or structures. Buro Happold modelled the whole building to determine if a naturally ventilated solution was feasible. The thermal model identified that the ground floor would remain comfortable, but that the upper floor would over-heat without additional ventilation. Unwilling to abandon the natural ventilation principle, the design team worked with the developer to establish a series of modifications to the base building:
Additional opening areas provided in glazing
False ceilings omitted at ground floor to expose slab soffits to improve thermal mass
Inclusion of the roof apex volume into the space by omitting false ceilings at first floor
High level ‘penthouse’ louvres introduced at the roof apex for high level ventilation
Addition of external solar control blinds
Introduction of deep raised floor for local cooling and potential future cooling needs
Addition of thermal mass in the form of heavyweight boards in the roof was examined, but when modelled, showed an insignificant improvement in summertime peak temperatures. A number of external shading systems were examined (modelling had demonstrated that internal blinds would be inadequate), with motorised blinds favoured for flexibility and daylight maximisation. The chosen material is a woven mesh, such that views out are maintained, whilst solar gain and glare are considerably reduced. Cooling could not be entirely eliminated – the heat loads generated by an IT hub room and some meeting rooms proved excessive – but self-contained direct expansion cooling units were used underfloor to avoid the need for a central chiller.
SAP required a canteen facility, with associated commercial kitchen. This was inserted into the north-west corner of the building, with a local supply and extract system shoe-horned into the roof space. Drainage had to be upgraded with the introduction of grease traps and new underground connections.
But perhaps the trickiest element of all was selection of controls. A full Building Management System (BMS) was introduced as part of the fit-out in order to control the balance of elements: motorised windows, motorised louvres and motorised blinds as well as heating and local cooling controls. This did not always prove successful, the local DX unit controllers being incompatible with the central BMS, as were the imported blind controls. Lighting controls – including daylight linking, movement detectors and local switching – were introduced, but usage patterns did not match design, and sensor locations and control logic had to be re-programmed to optimise energy savings.
Despite these teething problems, some of which were, perhaps, the inevitable result of the swift programme, the employees are delighted with their new offices – the lively interiors and open spaces a vast improvement on their previous working environments.
Another project, currently still being considered, seeks to take a more radically green approach. A small residential development situated in a tight urban location at Dublin’s commercial and Georgian heart, the client developed a comprehensive environmentally sustainable brief with the architect, Solearth Architecture, that considered every aspect of construction. The upper floor structure is timber-framed, joints specifically arranged to use the minimum amount of glue. Clay minerals embedded in geotextiles are utilised for basement tanking and radon protection, with floor surfaces formed from compacted earth rather than conventional screeds.
The roof is to be sedum – a low-growing alpine plant that provides insulation as well as an attractive, long-lasting finish – railings are bamboo and the walls are filled with cellulose (recycled newspaper) insulation. In building services terms, the design makes the most of the sheltered site and is substantially naturally ventilated – where mechanical ventilation is required, recycled cardboard ductwork is to be used. The heat source is a ground-water heat pump, with hot water provided by solar energy. In addition, the design aims to be PVC-free and to reduce electro-magnetic fields around the building. Such laudable thoroughness is to be applauded, but – and it’s a significant but – the cost penalty for such untried techniques proved prohibitive, so it is not surprising that the client is currently seeking a less extreme solution.
These projects illustrate some of the typical solutions to low energy design – modest but thoughtful additions to the building stock, projects that ‘go green’ quietly rather than overtly displaying their green credentials to public scrutiny. It is only by taking forward energy saving, environmentally sympathetic design solutions, one step at a time, that engineers and designers can actively contribute to the overall delivery of a built environment that touches upon the Earth lightly. Fine words are all well and good, but it is the doing of it that really counts.
Edith Blennerhassett, Buro Happold, Dublin June 2003
Background information for editors:
Press office and practice information
Buro Happold is a multi-disciplinary international practice of consulting engineers established in 1976 offering civil and structural engineering, mechanical and electrical engineering, quantity surveying, building services and environmental engineering, health and safety management, infrastructure and traffic engineering, ground engineering, façade engineering, fire engineering, computational fluid dynamics analysis, disability design consultancy, project management, urban design and a range of specialist CAD services.
