As temperatures rise, clients want more air conditioned working environments. But there's pressure in the opposite direction from the climate change levy and Part L. A guide from CIBSE is available for engineers seeking advice. Dr Hywel Davies examines Guide B2.
Bob Dylan has just produced a new album, but in the world of ventilation and air conditioning the theme song might be his sixties anthem, "the times, they are a changing".

Our increasingly hot summers are driving more people to install air conditioning. Most of these systems use energy, energy that is taxed through the climate change levy. And lurking just around the corner are the changes to Part L of the Building Regulations, due any day, which are going to introduce requirements for specific fan power and for the performance of air conditioning systems, to mention but two of the changes. Finally, as if that wasn't enough, there is a draft European directive on building energy performance to consider. Ventilating and cooling of buildings is a big issue and it's growing.

For engineers wondering how to respond to these various assaults on the habits of at least a generation, help is at hand. After nearly three years of hard slog, and a DTI aided research project, a new CIBSE Guide to ventilation and air conditioning has emerged. As well as giving up- to-date guidance on newer methods of ventilation and cooling, it addresses the thorny issue of greater co-operation between professional disciplines in the earliest stages of design. And it provides an up-to-date source of reference to a wealth of information published over the last decade.

Section by section
Guide B2: Ventilation and air conditioning is based on, and replaces, sections B2 and B3 of the 1986 edition. It has been revised to take account of developments in the intervening years. After a brief introduction, Section two describes an integrated design approach addressing location, orientation and structural form and their impact on the ventilation strategy for the building. This is important because some of the earliest decisions about form, fabric and orientation have huge implications for the ventilation strategy.

With the growth in single point responsibility in procurement, there is now far more scope for these issues to be addressed together. Section two provides new guidance on the strategic choice of ventilation strategy – should it be naturally ventilated or is it more appropriate to opt for a mechanical approach?

Section three describes the basic requirements for ventilation of offices, which are the most common type of non-domestic buildings. This is followed by sections reviewing the specialist requirements of a wide range of other building types, from television studios to transport facilities.

New additions to this section include assembly halls and auditoria, cleanrooms, computer rooms, atria and communal residential buildings. To coincide with the recent extension of Building Regulations to schools that section has been rewritten in consultation with the Department for Education. The section on museums has also been rewritten to reflect current thinking in this specialist area.

Section four gives detailed guidance on natural, mechanical and mixed mode ventilation systems and air conditioning, building on some of the basic issues addressed in section two. It also includes a section which deals specifically with the issues of night cooling and the use of thermal mass.

Section five provides information about a range of equipment used in ventilation and air-conditioning systems, in particular covering some of the kit used in natural ventilation, such as windows, louvres, roof ventilators, shafts, ducts and combined openings.

Several sections are relevant to the current changes in regulations, taxation and even procurement practices, PFI and its relatives all require greater teamwork.

Designing for the future
The guidance on integrating the services design with architectural considerations offers improved performance of the finished building handed over to the client. It can also increase the profitability of the PFI consortium, by ensuring that form, orientation and services strategy all work together. This will deliver better building performance and more energy efficient buildings. It will minimise future exposure to the climate change levy, which must be very likely to increase over time.

  Another new feature which has great potential is the table of performance requirements in Section two. This is included to encourage client requirements to be identified, in particular their implications for the ventilation strategy. It covers areas such as the required work patterns in the building, the required layout, whether cellular or open plan, the occupancy density and hours and the importance to the client of being able to change all these later on and still have a working building. Such flexibility is increasingly required, and careful attention to these issues is vital to its delivery.

A number of newer cooling methods are introduced to the Guide for the first time. These include:

  • evaporative cooling
  • desiccant cooling
  • ground coupled systems
  • night cooling
  • chilled ceilings and beams
  • displacement ventilation
  • heat pumps

We now understand that effective building ventilation is important to productive working. Effective ventilation doesn't happen by accident, and the new Guide will be an important tool in the hands of designers who want to deliver ventilation and cooling systems that satisfy client needs.

It is important for clients to realise that the costs of designing, installing and operating effective ventilation systems are small compared to the costs to the business due to poor ventilation. Over a system life of ten to fifteen years a 1% reduction in productivity will easily outweigh any 'savings' made at the design stage.

The new Guide B2 will help to avoid such false economies and deliver buildings which more fully meet the needs of their owners, operators and occupiers, which provide more productive places for the people who work in them, and which generate much lower carbon emissions.