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Open or Closed? It's neither...

Footprint reports on Ecobuild’s Passive vs. Active seminar

Ecobuild’s Passive vs. Active seminar focused on the appropriateness of passive and active ventilation strategies. Practitioners drew on lessons from different projects to share best practice in ventilation.

Neville Rye of WSP Sustainable Buildings Group spoke about how design can achieve better indoor air-quality. The most common cause of complaints about buildings in the UK is overheating; second is poor air-quality. Many of these problems could be prevented if user comfort criteria were properly considered from a project’s inception. The importance of understanding detail to the success of a ventilation strategy was demonstrated by CFD images showing how replacing top-hung windows with mesh protected sliding windows dramatically improved classroom ventilation. 


Devil in the detail: CFD visualisation shows a warm classroom and poor airflow with a top hung window.



Devil in the detail: CFD visualisation shows a cooler classroom and better airflow with a sliding window.

Crown House Technology’s Paul Hancock echoed the same concern, stressing that it’s not about designer choice but about always proposing the most appropriate solution.  This can only come from a rigorous understanding of a project’s context. Hancock offered a six point checklist:

1.       Understand client requirements and context – each project is different.

2.       Challenge the assumptions that the client presents to you.  For example, does the server you are cooling need to be that big or are there overall savings to be made with a more efficient but expensive one?

3.       Always factor the impact of decisions. Bigger windows may mean more light but also more solar gains.

4.       Consider implications of technology. Make sure users understand how the system should be operated.

5.       Use as few and simple solutions as possible. These are easy for users .

6.       Be an energy miser.  Every watt saved can add up to big savings for an organisation.

7.       Use what you have in as many ways as you can. If you have a concrete slab, use the thermal mass.


Dr. Rupert Soar of Nottingham Trent University concluded the seminar by giving us a look at a possible future.  He asked the question of how we get more efficiency out of fewer resources.  According to Soar, our current approach, especially where building airtightness and mechanical heat recovery is concerned, is reaching a point of diminishing returns. Soar proposes manipulating the geometry of simple materials to achieve extraordinary performance through 3D printing.  He believes that our current way of working - with expensive design and cheap materials - is set to change.  The future he proposes is one of cheap design and expensive materials.  Improvements in digital modelling and fabrication mean that, like nature, we will be able to do more with simple materials.  In the same way that a termite mound’s complex geometry creates a comfortable internal climate using natural materials, Soar is developing computer modelling and 3D printing to create simple materials that can intelligently regulate internal environments, or as he put it ‘control leaky stuff’.   Simple gypsum concrete can be transformed into a phase change material by manipulating its geometry.   Soar’s work gives us a window on possible sustainable materials of the future and what the practical implications might be. 

The message from this seminar was that there are no short cuts to successful sustainable design.  Only a diligent and specific approach to the requirements and details of a project will deliver real gains.

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