ARPAN JOHARI. Architect - AW Designawdesign.in/pdf/Thermal_Mass_Presentation_Guj_Uni.pdf ·...

13/08/10 AW Design. Ahmedabad

ARPAN JOHARI. Architect

THERMAL MASSTHERMAL MASS

Thermal mass (or thermal capacitance) is defined as the ability of a body to

store heat


Thermal mass is also known as Fabric Energy Storage, FES (The Concrete

Centre. 2005), thermal mass is a less exploited and effective sustainable

alternative to air-conditioning for combating the temperatures.

Thermal mass of the fabric, i.e. concrete or ground is effective in

maintaining the desired comfort levels.

They work on a principle that buildings with high thermal mass have a slow

response rate to changes in ambient climate.

THERMAL MASS

response rate to changes in ambient climate.

It benefits the buildings particularly in summer times, when concrete

absorbs internal heat gains to avoid over heating. This heat sink builds-up

towards accumulating higher temperatures at evening times.

Evening cooling of these buildings helps take off this excessive heat build-up

and it further moves on to the next day cycle


THERMAL MASS

Stabilising effect of thermal mass on internal temperatures

Source: Termodeck,2005


Thermal mass works on a simple principle of the slow response of concrete

to changes in the weather conditions.

This aids in reducing peak temperatures especially during summer days

when the internal heat gains are absorbed by concrete which prevents over

heating.

This property of high absorbance and low transmittance can delay the onset

of peak temperatures by upto six hours .

THERMAL MASS

This property of high absorbance and low transmittance can delay the onset

of peak temperatures by upto six hours .

This property is known as ‘Thermal Lag,’

This typically in an office environment happens in late afternoons of when

the occupants have left.


THERMAL MASS

Thermal Lag



THERMAL MASS – Case Study; TermoDeck

TermoDeck system uses high thermal mass of hollow concrete slabs for

delivering comfortable results.

The system comprises of a fan assembly, ducting and purpose built for

concrete slabs.

Through these slabs, warmed or cooled fresh air is distributed.

Fresh air supplied to the system passes through channels in the tube, which Fresh air supplied to the system passes through channels in the tube, which

facilitate prolonged contact between air and the slabs.

These slabs exhibit passive cooling or heating by either taking or adding

energy to the system.


Case Study - TermoDeck

TermoDeck using principles of Thermal massSource: Termodeck,2005



Source: Termodeck,2005Source: Termodeck,2005



The system reacts to thermal loads in four ways:

Summer days: warm ambient air is cooled when it enters the pre-cooled

hollow slabs. This cool concrete also absorbs heat generated from lighting

machinery, people and re-radiated solar gainsSource: Termodeck,2005



Summer nights: at night times, outdoor air is blown into the hollow

slabs. This assists cooling down the building frame to the next day.




Winter days: it helps during the cold winters as the tightly sealed and

highly insulated building envelope helps prevent heat loss from inside the

building. Heat from the rooms is extracted from them by using extraction

fans and is passed back to the slab which in turn conduits it in the other

activity areas Source: Termodeck,2005



Winter nights: this works by shutting the system at night. The daytime

heat gains are slowly distributed. If the building cools down prematurely,

which might happen occasionally, the sensors in the ceiling would turn on

the heating system. This would take of the load from the conventional

heating system and would hence assist in reducing energy related costs.




Stability of internal temperatures in a TermoDeck building


Reduces the capital costs of building materials by using modular

components.

Low complexity of services leads to lower maintenance costs. Great

reduction in the amount of using ancillary mechanicals like fans and chillers.

Reduces the need for false ceilings and ceiling voids. This leads to reduction

in storey heights

Advantages - TermoDeck

Reduction in moving parts outside plant rooms

Non complicated and short commissioning period

Different temperature zones do not demand for dedicated climate control

systems. One slab takes care of temperatures and ducting for upto 16

meters


Slabs provide both, radiant and conductive heating/cooling, owed to the

high thermal mass

Service and cleaning points allow for easy and cheap cleaning

Running costs as compared to air-conditioned buildings is lower by upto

46%

Advantages - TermoDeck

Maintenance costs are greatly reduced. Upto 13% for air-conditioned

buildings and upto 33% for naturally ventilated buildings

Thermal mass contributes to a great extent in regulating the building

climate as compared to buildings with mechanical ventilation




Annual Costs



Source: DETR Report

Energy Consumption


Reduced carbon dioxide emissions in the entire life cycle

Heat recovery of upto 90% from extract air stream leads to a greatly

reduced energy consumption pattern.

No temperature draughts. All the year uniform temperature stability

Fresh air is tempered within in the system, as compared to using an

expensive plant for the same

Advantages

expensive plant for the same

Fresh filtered air is supplied well in excess of the recommended 8L/second.

Exposure of the slabs to both, air and room temperatures helps to get a

better temperature stabilization

No need for radiators eliminates further problems of energy supply and

maintenance


It is virtually unobtrusive, both visually and physically on building interiors

and exteriors

Opening windows does not add any further loads to the system

Virtually no operational sound of the system. Further the sounds produced

by the fans are damped by the dense concrete slabs. It is highly effective in

the 125-500 Hz frequency range

Advantages


Acoustical Performance




Energy inputs by various systems




Life cycle costs over 25 year period


Thank you

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AW Design. Ahmedabad13/08/10

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ARPAN JOHARI. Architect - AW Designawdesign.in/pdf/Thermal_Mass_Presentation_Guj_Uni.pdf ·...

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