Friday, 28 April 2017

Health warning

The impact of indoor air quality on the comfort and well-being of students is gaining increased attention. Dr Hywel Davies, CIBSE Technical Director, summarises some recent research on the subject and describes the latest guidance on new schools design

The need to maintain air quality in schools is a hot topic - literally. The Government is scheduled to publish a revised version of Building Bulletin 101: Guidelines on ventilation, thermal comfort and air quality in schools. The document provides guidance on the design and construction of school buildings in order to provide good indoor air quality and thermal conditions to create effective conditions for teaching and learning. 

A draft of the proposed amendments has already been published. They call for the designers of schools in areas of poor air quality or in low emission zones to give careful thought to keep internal pollution within acceptable levels. One way of achieving this is to design a building to be airtight and then use an appropriate air infiltration system to help remove the harmful particulates, such as from diesel vehicles, from the air supply. For filtration to be effective, without consuming excessive amounts of energy, the filters can be incorporated into a mechanical ventilation system with heat recovery, although it is also important that they are readily accessible for cleaning and changing.

The Government is revising the guidance on school air quality to reflect
the increasing evidence of its importance
The 2017 publication will supersede the 2006 edition of BB101: Ventilation of School Buildings. The addition of the term “air quality” to the title reflects the increased importance to government and other organisations are now giving to maintaining good indoor air quality in schools.

One reason for the increased focus on air quality was the publication of the Royal College of Physicians’ report Every Breath we take: the life long impact of exposure to air pollution. This highlights the dangerous impact air pollution and poor indoor air quality is having on our nation’s health and in particular how exposure to air pollution may affect mental and physical development in children. The report explains that children living in highly polluted areas are four times more likely to have reduced lung function in adulthood, but improving air quality has been shown to halt and reverse the effect.

Improving indoor air quality in schools was a topic at the CIBSE Building Performance Conference. Speaking at the conference Prof. Dejan Mumovic, Deputy Director of the Institute for Environmental Design and Engineering at University College London, made reference to two recent research papers – one on the impact of carbon dioxide (and temperature) on student’s cognitive performance and the other on the economic benefit of the impact of reducing indoor exposure to nitrogen dioxide in children attending primary schools.

Children living in highly polluted areas are 4x more likely
to have reduced lung function as adults
Mumovic referenced a study undertaken in Saudi Arabia on classrooms with all female students aged 18-21. The research set out to understand the impact of indoor ambient temperature and carbon dioxide (CO2) concentration as an indicator of the effect of ventilation rates on student’s cognitive performance in educational buildings.

The study found that temperatures in Saudi classrooms are typically 20°C, with a high ventilation rate of 15 litres per second per person. These conditions were taken as the baseline for the study. Cognitive tests were then undertaken at classroom temperatures of 20°C, 23°C and 25° and with CO2 concentrations of 600 parts per million (ppm), 1000ppm and 1800ppm. 



When classroom conditions were at their most extreme, with a CO2 concentration of 1800ppm and temperature of 25°C, students took 72% longer to complete the cognitive tests and made 32% more errors. This demonstrates the importance of designing classrooms that can be kept at optimum temperatures for learning throughout the school year. 

Mumovic also referenced a study by the London School of Hygiene and Tropical Medicine.  This used  environmental and health data collected in primary schools to assess the potential economic benefit of reducing indoor exposure to nitrogen dioxide (NO2) in children in London. Nitrogen dioxide is a gas produced by road traffic and other fossil fuel combustion.  The study estimates that 82 asthma exacerbations per school could be averted annually by reducing outdoor NO2 concentrations. 

The study estimates that the monetary benefits of reducing children’s indoor NO2 exposure while at school could be as much as £60k per school from a parents’ perspective, using a willingness-to-pay approach.

82 asthma exacerbations per school could be averted annually by reducing
 outdoor NO2 concentrations.
According to Transport for London, there are 2270 schools within 400m of roads in London, so the number of primary schools likely to be affected is significant, as are the economic benefits of reducing NO2 levels, for example through road closures during school hours.

CIBSE has published TM57: Integrated school design to provide guidance on the environmental design of schools. The document is suitable for building services engineers and other members of the design team including: architects, contractors, client bodies and users, who have an influence on the design outcomes. It is available from http://www.cibse.org/Knowledge/knowledge-items/

In producing this Technical Memorandum CIBSE’s aim has been to provide simple and clear guidance to help steer both the design team and school staff towards creating places where teachers and children can become inspired. A checklist of criteria on its own will not constitute successful design -  school designers must also make the effort to visit existing school buildings and to study exemplar cases to fully experience the results of the design process, both good and bad. The design of school buildings is an area where engineering input from experienced building services engineers can prove invaluable, and have a long lasting and significant impact on pupil health and performance. Time spent in design can certainly deliver a long term dividend that makes it a good investment.


Friday, 21 April 2017

The next step

Fresh from its win at the H&V News Awards in the Best BIM Innovation award, CIBSE digital engineering consultant Carl Collins explains what BIMHawk is, and where it fits into the BIM landscape.

In Level 2 BIM products are described by 3-D geometry and by their accompanying technical information. The output from separate modelling systems, eg. architectural, building services, structural engineering are combined in a single common data environment to create a digital 3-D representation of the building and its systems. Using this model software can then enable the coordination of the mechanical and electrical services, for example, with the other building components such as the structure.

The same common data set, will allow an operative to select an object, such as a chiller, and interrogate its properties, such as when replacement parts are needed under planned maintenance. When collections of objects are joined to create a system, all of the objects in a system can inherit and share attributes, so potentially this would provide the planned maintenance schedule for a particular system, such as a chilled water system, for example, based on the collection of its components’ needs. It is the richness of the data that will determine the potential effectiveness of BIM as a maintenance tool.



Until now, very few building services product manufacturers have produced BIM models that incorporate data. Or, where data is available, it is often produced in response to a consultant’s questions on a bespoke basis and not in a standard format. Now that is about to change with the CIBSE and NGBailey launch of the BIMHawk website.

BIMHawk is a free online toolkit and suite of software programmes developed specifically to speed up the development, dissemination and adoption of standardised product data. CIBSE recognised the need for standardised product data back in 2011, when it was apparent that manufacturers were working in isolation to create their own, bespoke product libraries, often in response to demands from customers for data for use in a BIM model.

A lack of consistency between manufacturers'
data has held BIM back
BIM is supposed to make the construction and maintenance process simpler, faster and cheaper. However, CIBSE recognised that many of these bespoke product libraries suffered from flaws of limited compatibility and interoperability between BIM modelling platforms. And without an agreed industry product standard there would be no consistency in manufacturers’ data, which meant that many of the potential benefits of BIM would fail to materialise.

CIBSE set out to establish a set of common parameters for different building services products through its creation of Product Data Templates. A PDT is a collection of parameters that describe a particular product, or product type. Only parameters useful to a designer, contractor or maintainer are included on a CIBSE PDT. To ascertain which parameters should be included on a particular PDT the Institution worked with trade associations, competing manufacturers, designers and facilities managers.

To date, PDTs produced by CIBSE include those for cooling coils, fan convector units and cable tray systems. For the full, up-to-date list go to www.bimhawk.co.uk. To allow manufacturers to create, complete and upload PDTs online CIBSE teamed up with Paul Marsland, design and BIM development manager of NG Bailey. The BIMHawk website is the outcome of this partnership. The website also allows PDTs to be integrated into BIM authoring systems.

One particularly useful feature of BIMHawk for product manufacturers is that for every parameter added, BIMHawk will check for that parameter in the BuildingSMART Data Dictionary to see if the parameter name already exists. BuildingSMART is an international organisation set up to enable BIM models to be exchanged from one platform to another through the use of a platform neutral language called Industry Foundation Classes. To do this each individual object parameter must be created with a common globally unique identifier, or GUID. If a parameter with the same name has been defined previously, BIMHawk will extract its GUID. If not, BIMHawk will generate its own definition and associated GUID.

When a manufacturer populates a PDT with product specific data to digitally define a particular product it is called a Product Data Sheet (PDS). Manufacturers can upload their product data sheets to BIMHawk. This will enable consultants, contractors and commissioning engineers to access standardised data and to compare products from a variety of manufacturers on a like-for-like basis to make specification quicker and easier. In effect, BIMHawk becomes a catalogue of catalogues.

BIMHawk will soon contain data useful to other sectors, such as water
BIMHawk is not just for building services engineers, it is designed to be of use to any construction discipline. To that end CIBSE are working with the Landscape Institute, BIM4Water, BIM4FitOut and others to create a much larger product database. Currently the PDTs outside of the CIBSE remit are not yet on BIMHawk, but they will be soon.

Alongside the website, CIBSE and Marsland have developed a Revit plug-in to allow BIM models to acquire product data in a structured format from a PDT. The plug-in removes the need for manufacturers to create new product models from scratch.What’s more: the next iteration of the Revit plug-in will bring the values from the PDS into the BIM model. This will allow designers to look through the data sheets of different manufacturers to see which products are the best fit for a particular design concept and then import the data on the size and performance characteristics of that product.

With the launch of BIMHawk, CIBSE will help to speed up the development, dissemination and adoption of standardised product data. This will be a massive step forward in enabling collaborative working and the exchange of data and information throughout a project’s lifecycle in a consistent manner, something that until now has been missing.

Thursday, 13 April 2017

Template for success

BIM is an area of constant innovation, but without the work of hundreds of volunteers this pace of change wouldn't be possible. Iain Paterson, Business Development Manager at UK fume cupboard manufacturer Safelab Systems Ltd. gives a manufacturer’s account of creating the all-important Product Data Template (PDT) for a product category.

Since they continuously expel conditioned air from a building, fume cupboards are an extremely influential component of the building services engineering remit for many educational and research   buildings. In a typical new university STEM building, where there might be from 30 to 130 fume cupboards, a complex interplay of face velocity, air flow rate, make-up air requirements and discharge velocities will have an impact on the design of HVAC systems and the required duct diameters and fan specifications.  The design will have a significant impact on the awarding of
BREEAM credits.

Modelling the effects of various fume cupboard configurations on building
services specifications requires product data to be in a BIM environment

In order for consulting engineers to be able to quickly model the effects on building performance of changing parameters such as face velocity or sash height, these parameters need to reside in a BIM environment, and consistently so; the federated BIM model that is crucial to compliance with Level 2 BIM relies on data being stored and exported in a consistent format.
As is the case with many other companies, our product data is set out in technical data sheets and operating manuals.  In the BIM world we fully recognise this data must be readily available in a digital format for uploading into software such as Revit, for example.

Discussions about how to maximise the usefulness of our BIM models
for consulting engineers led to our involvment in the PDT project
But where to start?  Discussions about BIM models with Rich Cole at SES Engineering led us to approach CIBSE to instigate the creation of a new PDT.  A PDT is a document in a specific format containing the parameters required to describe a product for the purposes of BIM.  The PDT needs to cover everything from the key product dimensions needed by architects, to performance data required for consulting engineers' calculations, and the maintenance schedules needed by facilities managers following project handover.


Helpful discussions with Carl Collins, CIBSE digital engineering consultant, provided us with the official sanction to generate the official PDT for our product category.

So what’s involved? For all the sophistication of the software surrounding BIM, it must be emphasised to any manufacturer considering creating one that a PDT is, in essence, simply an Excel spreadsheet, and a standard Excel template which forms the basis of all new PDTs is available from CIBSE.  Whilst the PDT’s format is determined by CIBSE, it is for us as the PDT originator to propose which product data to include and exclude.

The level of detail is key.  Just as in a well-designed ‘lean’ Revit model to which the product data will be attached, a PDT’s level of detail should be just sufficient for purpose.   As a manufacturer we hold a profusion of product data that would never be used in a BIM environment. At this point we found discussions of our initial thoughts with Buro Happold were invaluable. As a user of the data they were able to advise which parameters were critically important and in which units of measurement would be preferred.

A well-designed BIM model should have just enough information to be useful
Eventually we had refined, buffed and polished our draft PDT to the point where we felt it was ready for the peer review stage, in which our trade association, GAMBICA, is now circulating our draft PDT amongst its members. The PDT which emerges will be put out to public consultation, before ultimately being signed off by a chartered engineer under the auspices of CIBSE.

As the originators of the PDT, we will always be consulted by CIBSE should any changes to it be proposed.

We are proud Safelab is playing a role in the CIBSE PDT project, whose outcome will help significantly in enabling the full potential of BIM to be realised, and look forward to the next step.
For any manufacturer thinking of generating a PDT, please get in touch at www.safelab.co.uk – we would be more than happy to share any knowledge and experience of the process. You will be placing yourself in the enlightened vanguard of your industry!

Acknowledgements
We have been helped on our PDT journey by the generous input of Jose Fandos at Buro Happold,
Rich Cole at SES Engineering Services, Eugene Sayers at Sheppard Robson, Tim Collins at GAMBICA and Carl Collins at CIBSE.