Thermal labyrinths
Contents |
[edit] Introduction
A thermal labyrinth decouples thermal mass from the occupied space, usually by creating a high thermal mass concrete undercroft with a large surface area. Decoupling the thermal mass means it can be cooled to a lower temperature than if it was in the occupied space.
This stored ‘coolth’ can be used to condition the space in hot periods.
[edit] Options
The labyrinth layout needs to balance optimum thermal storage with the air resistance of the system. Creating air turbulence, by increasing the roughness and incorporating bends, improves heat transfer. However, incorporating too many bends may increase the air resistance beyond the point where the system can be part of a passive or naturally ventilated scheme.
Thermal labyrinths are suited to new, mechanically-ventilated buildings with cooling demand that are located in climates with a large temperature difference between day and night.
[edit] Size and output
As labyrinths are often constructed directly beneath a building, only the sides and floor of the labyrinth are in contact with the earth and the top of the labyrinth is directly coupled with the building. This means that the labyrinth needs to be well insulated from the building to prevent heat transfer.
The earth contact of the labyrinth gives the benefit of steady ground temperatures, however, the undisturbed ground temperature cannot be used in calculations, as it will be affected by the presence of the building and the operation of the labyrinth. This means that optimisation of the design requires a complete thermal simulation of the system.
When the ambient air temperature can itself meet the cooling requirements of the building, the labyrinth can be bypassed so that its cooling potential is retained for use during peak conditions.
During the unoccupied period when the ambient air temperature is low, night cooling is used to ‘charge’ the labyrinth.
[edit] Running costs
Regular inspection and cleaning of the labyrinth are recommended, although thermal labyrinths are generally virtually maintenance free. The major cost that can be incurred is when fan power is required to supply air through the labyrinth.
[edit] Summary
Thermal labyrinths can be integrated into a building's structure to provide free cooling in the summer and pre-heating of air in the winter. They can have high capital costs, but over the life of a building,
can yield substantial savings by reducing peak demand for cooling and heating.
This article was created by --Buro Happold, 17 March 2013, based on a 2008 article in 'Patterns'.
[edit] Related articles on Designing Buildings Wiki
- Air source heat pumps.
- Dynamic thermal modelling of closed loop geothermal heat pump systems.
- Earth-to-air heat exchangers.
- Geothermal energy.
- Geothermal pile foundations.
- Ground energy options.
- Ground pre-conditioning of supply air.
- Ground source heat pumps.
- Thermal mass.
- Trombe wall.
- Types of ventilation.
[edit] External references
- Ingenia, Going underground September 2006.
Featured articles and news
The continued ISG fall out, where to go?
Support for ISG contractors, companies and employees.
New HES national centre for traditional building retrofit
Announced as HES publishes survey results which reveal strong support for retrofit.
Retrofit of Buildings, a CIOB Technical Publication
Expected to become one of the largest activities in the global construction industry.
The ECA industry focus video channel
Keeping update with the industry session by session.
Over 25 recorded informations sessions freely available.
AT Awards 2024 ceremony East London October 25th.
Revisiting the AT community at the 2023 awards evening.
The Community Housing Fund and built affordable homes
CLTN reviews the impact of the Fund and calls for extension.
The grading system of the Regulator for Social Housing
A background, an explanation and ten recent enforcements.
Construction, repair and maintenance. Book review.
Putting new life into a city with a 1900 year history.
BSRIA Briefing 2024: Sustainable Futures speakers
Redefining Retrofit for Net Zero Living 22 Nov.
Wall of support for post-Grenfell regulation of electricians
Call for a shake-up of the construction industry highlighted on radio.
Digital sustainability through future AEC tools
Bringing together industry and academia to meet challenges.
Skills gap for net zero highlighted to Minister for Industry
ECA convenes roundtable discussion at Portcullis House.
Evidencing Net Zero with the new UK buildings standard
Pilot version with detailed excel proforma out now!
Scottish Building Safety Levy, in consultation
From direct remediation and the RPDT, to the costs and alternatives.
Waves of warmer homes grants for the rental sector
Boosting energy efficiency standards for all rented homes.
A refocus of the National Planning Policy Framework
Key terms described in brief, as the consultation closes the evening of the 24th.
Fortified farmhouses of the unruly 16th-and 17th-century borders.