All the elements of the building envelope - roof, walls windows, etc. need to be insulated for keeping the internal ambience from excessively heating up or cooling down with the change in external weather conditions.
Insulation saves money, increases home comfort, and protects the environment by reducing both energy use
By reducing 1 unit of power, you save more than just that. A reduction in demand means savings in the cost of generation, supply & distribution of power as well.
Buildings Consume More Energy Than Any Other Sector, Transport or Industrial
Buildings are the Largest Contributor to Climate Change, are responsible for emission of 30% of the total Green House Gases.
74% of the total Electricity produced is consumed by buildings in the developed world.
Source for 75% of this energy comes from the depleting, non-renewable, fossil fuels.
This global energy consumption is linked with increasing rate of Carbon dioxide & other Green House Gas emission , leading to rapid climate change.
Since buildings are the problem, their construction should be such that they themselves become the solution, by lowering the current energy demand.
Energy efficient buildings are the answer to the pressing need for achieving economic gains by reducing the need for more power generation & its distribution.
Awareness, promotion & use of CFLs instead of light bulbs is not sufficient to lower our energy demand, the focus needs to shift from uninsulated to well insulated, environment friendly & comfortablel homes & buildings as this will play a critical role in slowing down climate change.
Bottomline - by meeting self imposed target savings, all of us end up with better designed, more comfortable constructions & save money in the bargain!
Roof & walls account for the maximum infiltration, about 50-60%.
Choice of insulation material depends on many factors :
* level of insulation provided by the material over average building life
* basic strength or rigidity requirements
* moisture and fire resistance
* compatibility with adjacent materials
* safe for humans and the environment
The most common issue surrounding the long term performance of insulation is loss of R-Value over time & moisture build up within insulating layer.
Independent testing of the commonly used insulates have shown that after 15 years of use EPS retained 94% of its R-value, while XPS & PUF had only 52% & 53% respectively.
The results further revealed that 4.8% water absorption by volume was found in case of EPS, while it was 19% and 14.5% in case of XPS & PUF.
Comparison of Per unit Cost of insulation material over annual savings in energy cost per year for the various options gives an idea of the payback period, which is shortest with EPS.
Heat ingress takes place by conduction, convection & radiation.
Solar heat comes inside buildings mostly by means of conduction, through heated roof, walls, doors & windows, floors & air leaks in intersections and cracks.
Insulation combined with waterproof layer on roof & walls checks heat gain by both conduction & convection.
Most of the incoming Radiant heat is thru glass doors & windows, white tiles can reflect only a small percentage. Unfortunately, they can do so for only a short period as in a tropical country like ours, dirt & dust deposits on these tiles further reduce their effectiveness.
The durability-product life, stability of insulating properties- whether or not it decreases with age, are vital factors that should be considered when selecting an insulation product.
Ideally, the product life should match the life of the building!
Finally, if the gradient is provided by a layer of soil or mud phase (as is common), improper sloping can cause water logging & seepage cannot be prevented if this goes unchecked for a considerable period.
Waterproofing alone cannot prevent structural damage or protect the building, by itself it's effectivess is also not long lasting due to its brittle nature.
Cracks on the roof are caused by daily expansion & contraction of the various layers that are part of the roofing structure. They become hot due to solar heat in the day & cool down after sunset.
These different layers - the roofing slab, waterproofing layer, external tiles & the finishing plaster on the terrace all expand & contract at different rates as their capacity to absorb heat & release it varies.
However, if an insulating layer is introduced on the external surface, the heat cannot penetrate into the Roof slab & life of the structure is thus protected & prolonged.
Thermal insulation is dependent on the following features of a product :
thickness & density of the insulating layer which depends on
- THERMAL PERFORMANCE, i.e. its low thermal conductivity or K-Value, and
- THERMAL RESISTANCE , i.e. its high R-value
both of the above are directly dependent on the
- material\\\'s specified thermal permeability or lambda ( l ) value,
- its moisture resistance
- its dimensional stability and
- stability of the insulating properties, i.e. no deterioration with passage of time.
Most important criteria for insulation (other than the obvious one,(i.e. Recovery & Payback period)- in order of priority :
* what is the thermal value that is to be achieved - product choice gets limited in case of internal insulation as some materials can be a fire hazard if used internally
* what are the materials & their thickness that can provide the target U-Value for Roof or Wall - some may not be suitable for indoor use & anything more than the average thickness of 2-4 inches will result in loss of expensive floor space with internal application
* the size of the construction & the cost of investment - external insulation is generally faster , cheaper and lasts longer
* prolonging building life - external insulation layer protects both the building envelope & the waterproofing layer and also adds to the life of the structure
* the internal space available - this decreases with internal insulation
* choice of exterior & interior finishings - any number of options are possible with external insulation, also no constraints in redecoration of internal walls & ceilings
* time constraint - a whole block or an unusually large terrace can be insulated in one go, conveniently & without any disruption to indoor activities
* taking care of thermal bridges , and
* interstitial condensation - stage at which insulation is being introduced .
External insulation is best incorporated in the building design stage itself since
for roof - overhead pipes, water storage tanks, outlets, vents, parapet wall heights, etc. and
for walls - scaffolding issues ,
may challenge a successful execution
With externally insulated walls & roof, you save on lower tonnage of cooling equipment that will be required in your rooms.
The interiors will cool faster & retain the same for a longer duration so AC will run for a shorter duration.
The savings in lower electrical consumption will ensure that you recover your investment.
On an average, the return (payback period) on your insulation investment will be < 2 years with KOOLTILEs for Roof and EIFS for walls..
Last, but not the least, proper insulation makes the building stronger, durable & prolongs the structural life of the construction. So for many years, you get to save on building maintenance costs as well!
This concept of insulating with soil used to work in old constructions which had high thermal mass from thick walls & could support a heavy roof that acted as a thermal barrier.
Nowadays, such constructions are expensive and there is wastage of costly floor space.
Most buildings today are made of cost saving lightweight construction materials to further reduce labour cost & construction time.
At the time of constructing a new roof, expenses are incurred on materials for the RCC Slab, a slope for gradient, waterproof layer, a finishing layer & labour charges to complete the work.
By investing wisely, over and above these standard costs, spend an additional 15% on a well designed, tested, thermal bridge free, environment friendly & long lasting insulant such as KOOLTILE, and you get -
- a roof which is maintenance free for the next 10-15 years!
- a stable, durable structure, without worries of damp interiors, seepage or leaking ceilings
- comfortable indoor temperature, all year round; even without Air Conditioners there is a minimum drop of 8 degrees C in the hot summer afternoons!
- if you also go for external insulation of the sun facing walls, there is a difference of another 5-7 degrees C in the rooms.
- in total, you will save over 50% in your power bills during the months of peak consumption