A lot of Georgian Dublin was consigned to the skip in the late 1960s, a victim of overzealous redevelopment. Much has survived to preserve its unique character, but the coffee bars and bistros are increasingly cosmopolitan. It takes busking urchins bawling out "Cockles and mussels" to remind the cappuccino addict that this is Ireland – not London, Paris or Frankfurt.
Visiting members of ASHRAE were in no doubt. For many Ireland is their spiritual home, which makes it an ideal venue for an Anglo-American conference. However, two parallel sessions held over nearly three days of the conference means it's only possible to give a brief overview of the event. Here's what we found worthy of note.
Sustainability
From the opening oration by CIBSE innovation champion Donald Leeper, sustainability was a recurring theme. The act of being sustainable, explained Leeper, was increasingly the responsibility of the individual. While ASHRAE and CIBSE can devise the ways and means by which buildings can be environmentally acceptable, "frankly," he said, "it is up to us to get on with the doing".
Those who have been "walking the talk" include AMEC's Andy Keys, who presented work by AMEC and Loughborough University on ways to minimise waste during the construction process. Over 70 million tonnes of waste is said to be created every year by the industry, which equates to around 24 kg/week for every person – four times the rate of household production.
After auditing seven building sites, Keys reasoned that a waste reduction policy should begin at the design stage. Designers, he said, should focus on materials, design complexity, communications and co-ordination.
Keys concluded that there are several mechanisms the industry can adopt. Among these are greater use of prefabrication, standard components, what Keys calls "realistic" components in terms of size, capacity and specification, and the use of reclaimed (and recyclable) materials.
Overall, he says, reducing waste depends on understanding how and why it is generated in the first place. (All this will be examined in more detail in a forthcoming BSJ article).
The ASHRAE's Richard Hayter reported on research into sustainability carried out by the US National Renewable Energy Laboratory. Among his more frightening statistics was that 81% of all new homes in the States are being air conditioned.
What this means in terms of future CO2 emissions was rather glossed over, but Hayter did claim that non-cfc chillers in the US commercial sector are likely to be 40% more efficient than the cfc units installed 20 years ago, contributing to a reduction of 7 billion KWh/y.
Among the useful advice to emerge from Hayter's presentation was the mention of a Sustainable building technical manual (Bernheim & Reed Public Technology Inc, 1996) and the US Green Building Council's, Local government sustainable buildings guidebook. Both of these publications suggest they might provide guidance applicable to the UK and beyond.
The full conference paper contains two case studies which, while highly specific to their context – Colorado, feature energy efficiency technologies with which most UK engineers would be instantly familiar: daylighting, solar shading and Trombe walls. On one project oversized evaporative coolers are claimed to save $30 000/y in chiller operation and fan power. Unfortunately data on kWh/m2/y was not made available, which precludes a comparison with similar UK buildings.
It was faintly reassuring to discover that US designers have as much trouble as their UK cousins in designing and calibrating lighting controls. Even when daylight and motion detectors were recalibrated, occupants complained that the spaces were too dim.
The authors claimed that the psychological aspects of daylighting may not yet be well understood, but they went on to say that the furniture and surfaces were predominantly various shades of grey. A bit of a hint there, one would have thought.
A co-authored paper delivered by the BRE's Denice Jaunzens offered some useful guidance on designing for flexible building services. The greater freedom required by the client to accommodate office churn, cellularisation or simply the ability to cope with a wide range of small power loads, the greater the degree of flexibility that is required in the m&e services (table 1).
The answers are largely common sense: keep designs simple and avoid reliance on short-lived, quick-fix technologies. Shell and core plus tenant fit-out makes buildings easier to adapt. Structured cabling, modular wiring and wireless communications make systems easy to reconfigure. And finally, only design-in overcapacity (such as lifts, risers and main capacities) when it is too expensive to add later.
The case studies
Two sessions were dedicated to case studies, some on buildings, and others on the construction process.
David Arnold and Bjarne Olesen gave separate papers on experience with embedded hydronic pipe systems for cooling and heating buildings. David Arnold described the Barclayslife building in Basildon, which relies on cooling pipework in pre-cast concrete slabs as a means of improving the thermal response of the building structure, while Olsen's paper concentrated on experience with such technology in mainland Europe.
Dr Arnold's paper – another one worth downloading from the CIBSE CD-Rom – describes how the services designers developed the concept of chilled slab as a means of accumulating low grade cooling energy and improving radiant effects. By looping plastics pipes around a profiled steel frame and encasing the resulting matrix in concrete, the designers were able to produce a slab with a steady-state cooling rate of 64 W/m2 – similar performance to that of a radiant chilled ceiling.
The controls had to be configured to prevent conflict between cooling the slabs with water and cooling the surface using overnight ventilation. BSRIA tested a slab with this in mind, and reported that the time to charge the slab was between 3.5 and 4 h, with a 30 min time lag between circulating the water and seeing the effect at the slab surface.
That lag was then included in the controls logic. In addition, the controls were set-up to either continuously charge the slabs in proportion to the rate of cooling, or charge it intermittently by pulsing the circulating pump.
Bjarne Olesen's paper explored the recent history of embedded heating/cooling systems using several buildings in mainland Europe. Hydronic heating systems are the norm, with the pipes embedded not only in soffits but also in walls and floors.
Olesen's paper gave a detailed analysis of three recent buildings benefiting from embedded systems: an office building in Munich, a museum in Bregenz, and a new office building in Hamburg.
Bjarne's studies show that, used wisely, embedded systems can cope with far higher cooling loads than all-air ventilation systems. As always there are riders. First, the ventilation systems must be operated to avoid dewpoint being reached on any of the cooled surfaces. Second, as the heating and cooling capacities of the systems are limited, they require careful design. They will only remove sensible gains from a space, and latent gains will need to be removed by ventilation, albeit one scaled down from having to cope with space cooling functions.
Other case studies worth a read include Peter Simmonds' very detailed analysis of conditioning large structures. Simmonds' paper describes a method of conditioning buildings with large internal areas by simply concentrating on the areas occupied and 'ignoring' the remainder.
He cited Bangkok International airport as an example, where a 1 million ft2 [sic] glazed roof added to the problems of unwanted temperature changes. A number of computer tools such as BEANS and TRYNSYS were used to develop a mixed mode system which includes variable volume displacement ventilation, shading louvres, low-E coated glass and a radiant cooled floor. Control strategies were an important part of the project, developed to optimise energy use, and ensure energy flows concentrate on the required areas, reducing the building load.
“For building simulation to penetrate the services profession...there is a need for appropriate training and professional technology-transfer initiatives”
Malcolm Tait of Edinburgh engineering consultant K J Tait Engineers described his firm's effort at partnering and cross-disciplinary working on a scheme to design the new Sellic Library for Edinburgh University. The time taken to design and modify the scheme was reduced by the fact that all the team members worked "within five minutes walk from each other", which enabled regular informal meetings to take place.
The specialist suppliers and clients were brought into the meetings at an early stage and modelling and testing continued throughout the process. The variety of lux levels required in a room that needed certain levels for shelving areas and others for seated working areas, while at the same time allowing for the future change into a mainly computer-based facility, were compounded by the low angle sun which hit the building from the west.
The exclusion of brise soleil due to interference with wind use for ventilation patterns brought about an innovative solution to the glare problem: prestressed stainless steel mesh which is normally used in sewage plant filtration will be attached 15 mm from the glass face. Internal roller blinds could also be added.
Construction process
On the construction process, AMEC's director of innovation Dr Mike Murray spoke openly about the experience of setting up an anglo-American joint venture. Murray recounted the history of International Design Associates, a shotgun marriage between AMEC and CUH2A, a US-based architectural practice. The catalyst for his arrangement was pharmaceutical giant Pfizer, which wanted a strategic collaboration to deliver a particular project.
Murray's paper concentrated on the methods by which the two very different organisations attempted to resolve their cultural, financial and day-to-day working differences. This involved workshops, games and various forms of analysis.
However, the main differences, which proved terminal to the joint venture in the long-term, were not so much cultural as practical. One of the biggest problems was determining precisely what was included in a designer's hourly rate. US overheads are calculated differently from those in the UK, so it was difficult to apportion costs equally among the designers, inclusive of salary, holidays, and benefits. In the end the shelving of the project plus the cultural differences drove the joint venture to disband. But all was not lost. AMEC has since bought a US practice and rebranded it AMEC Inc.
Computer design tools
Vince Murray and Ken Beattie of Dublin Institute of Technology took delegates through textbook application of dynamic simulation to test the validity of a natural ventilation strategy. By using Ole Fanger's PPD thermal comfort index, the researchers were able to demonstrate the differences in internal comfort conditions in different parts of a naturally ventilated building.
All good stuff. But five years on from the ground breaking research that revealed the fallibility of such models, there are still no recognised data sets that designers can use to check their modelling results. "Accuracy," warned Murray and Beattie, "is dependent on users' experience." This was echoed by Jan Henson and Joe Clarke of Eindhoven and Strathclyde Universities respectively. For building simulation to penetrate the services profession, they argued, there is a need for appropriate training and professional technology-transfer initiatives.
"As the technology becomes more widely applied, the demands on simulation programs will grow," they said. "While this is welcome...it is also problematic because the underlying issues are highly complex." In future, they argued, all programs must be able to operate on the basis of uncertainty bands applied to input and output data. Second, validation and calibration testing procedures must be agreed and routinely applied. Third, program interoperability must be enabled to support multi-disciplinary design procedures. Finally, ways must be found to place program development on a task-sharing basis to ensure the integrity and extensibility [sic] of future systems.
Paul Kingston of Hoare Lea discussed the possibility of integrating current cfd data into an interactive virtual reality process. His presentation left the audience with an air of excitement at the thought of "immersive environments" where user control is viable and achievable. Talk of automatic fly throughs of 3D cad drawings and simply putting on a set of 'glasses' to enter a 3D room where a joystick, mouse, or even an intelligent glove can be used to open doors, manipulate objects and test how systems will work brought the industry truly into the 21 century.
AMEC's Kevin Mitchell delivered a useful paper on the use of simulation modelling to develop the design of an entrance atrium to a four-storey office building. A paper worth downloading from the conference CD-Rom.
In short, Mitchell used airflow modelling to fine tune the air conditioning scheme. By reducing direct solar gains through the use of novel external solar shading, the designers were able to optimise the location of supply air terminals, (and the volume of supply air) to target the occupied areas. The design air volume was reduced by 40% and the PPD vastly improved to below 7%. The designers saved £25 000 on the cost of mechanical plant in the process.
Design tools
James Hill of the US Building and Fire Research laboratory gave an interesting paper on BEES, effectively a North American version of the ENVEST environmental assessment software.
Like ENVEST, BEES enables designers to run checks on the environmental qualities of construction materials. The program is available as "freeware" from bfrl.nist.gov/oae/bees.html, but being a 5 Mb file it will take time to download.
Hill also described the LEED program (the US equivalent of BREEAM) developed by the US Green Building Council. This program enables an environmental assessment of a building in five areas: site issues, water, energy and atmosphere, maintenance and recycling, and indoor air quality.
Weighted scores are given to these factors which enable a building design to be judged to a bronze, silver, platinum or gold standard. The software can be downloaded from www.usgbc.org. The program is not as impressive as BEES, but it is linked to current ASHRAE guidance. As delegates said, there is a message here for CIBSE and its relationship with the BREEAM scheme.
Energy
Two excellent papers from two established doyens of energy analysis – John Field and Phil Jones – moved an old subject a few steps further forward.
John Field has analysed the performance of buildings in the UK, the US and Sweden to establish the opportunities for harmonising the various national methods of assessment. Field researched seven energy assessment methods – three each from the US and the UK, and one from Sweden – and listed the virtues of each. Field found that, being a regulatory code, California Title 24 is a particularly detailed energy method that could inform regulation in other countries (table 2).
While harmonisation of these methods would require more work, Field concludes that the large amount of data needed to generate each standard could at least be pooled. That way standards might reach a better degree of consensus, such as what constitutes acceptable fan power.
Phil Jones gave a more detailed treatise on energy benchmarking in Northern Ireland. Jones has trawled data from 2000 buildings in the Northern Ireland public sector estate and classified it into 16 building types as a means of informing new energy benchmarks.
Electricity and fossil fuel consumption data was graphed against floor area for each of the building types, and the data used to establish typical and good practice benchmarks. Jones' reported that the preliminary data had provided some useful energy benchmarks for a range of public building types, from nurseries and schools to police and fire stations.
What we missed out
Lots, unfortunately. But that's not to say that Building Services Journal is going to forget them. Over the coming months the Journal will be publishing condensed versions of many papers, from Nick Bullen's experience of using fabric diffusers in a student cafeteria to Dr Gareth Redmond's jaw dropping predictions for nano-technology.
Source
Building Sustainable Design
