Labyrinth
Posted: September 18, 2009 by Gary, Category:Building Regulations, Sustainability, software
In this week’s blog I’d like to focus in on the potential of using the earth as an energy resource for buildings. In particular I’d like to look at the idea of incorporating underground labyrinths in a building’s design. These underground labyrinths are a type of thermal mass energy storage system and are not a new idea by any means but the use of the earth as an energy resource does tend to be overlooked.
Nature has used the earth as a way of creating a comfortable living environment even in the most severe external environment. For example the Barossa Termite, the great engineers that they are, build massive structures with fully integrated passive temperature control. So much so that they control the environment in which they live to within 1ºC throughout the year.
They use the mechanisms of thermal mass and evaporation in the main to control the temperature within their living environment. They construct underground chambers through which the outside air is drawn. This underground chamber is constructed to have a large surface area with the ground which cools the air on a hot day and warms it on a cool day. Even when this engineering marvel is exposed to extremely hot conditions the termites adapt and make the journey tens of metres down tunnels they have created to get to the water table to collect small quantities of water and bring them back up to place into the system. In this way they are supplementing the basic thermal mass idea with evaporative cooling. Clever eh…
These basic physical principles are transferable to model contemporary building design and can be effective when well thought out in reducing both energy consumption and peak demands on infrastructure which we here at IES get a real kick out of.
Although the thermal flywheel (room coupled thermal mass) which can be modelled very successfully in the software produced by IES is being worked into building design more and more in the UK the potential for heat exchange with the ground through large concrete heat stores which are commonly called labyrinths is rarely utilised in the UK. In Australia where I was based for the last 10 out of the last 12 months this idea is used with good effect.
In Melbourne where we (IES) have based our Australian office there is a great example right in the heart of the city of a labyrinth air system being incorporated into building design. It is at Federation Square and is used to supply air to the atrium like street associated with the Museum and when cooling is not needed in the atrium air is diverted to serve the galleries in the museum itself.
The labyrinth was formed from rippled concrete walls which were used to construct long air paths for the air to flow down.
During the day in Melbourne the external temperature can go over 40ºC in summer but at night the external temperature gets cool. This allows the thermal mass of the labyrinth to absorb the heat of the day and the cool air of the night purges the structure of heat and leaves the thermal mass of the labyrinth cool for the following day. The Barossa termites referred to earlier have inspired a system of evaporative cooling using stored rainwater to be incorporated into the labyrinth design.
The use of advanced dynamic thermal simulation modelling, which the IES Pro suite does so well, demonstrated the temperature benefits of the techniques in place at Federation Square.
The design has proved to be very successful keeping the Atrium space at comfortable temperatures even when the temperature outside is at its most extreme, eliminating the need for mechanical cooling which has saved significant running cost. In the winter the labyrinth mass storage system also provides some heat energy to the atrium space.
See http://www.federationsquare.com.au/index.cfm?pageID=28 for more information.
Till next time,
Gary
