What Insulation is best for my home?

All buildings are not the same .Neither are they located in a particular single geographical region. Their needs too may differ, for example whether it's heating or cooling that you require or whether it's both. (In which case which requirement prevails longer).The following information gives a better idea to plan this out.

• Climate prevailing at the site
• Space temperature you would be happy with.(low temperature setting will cause lesser loss of heat)
• Suitability, acceptability (by local regulations etc) and the convenience to insulate.
• Life span and durability (some are susceptible to moisture, material may settle soon and loose profile, may deteriorate faster etc.)
• Mode of heat transfer (whether conduction , convection or radiation is prevailing more)
• Building architectural design, orientation, use of glass in the building envelope etc. (for example whether outsulation is possible, air tightness, vapour permeability, forced or passive ventilation, possibility to use low-e insulated glass etc).
• Toxicity of the material (short term or long term)
• Sustainability, Carbon foot print, environmental friendliness and ability to recycle.

Insulation options

The types of building insulation may be broadly divided as;

• Structural
• and, Non-structural

Non Structural building Insulations

The following is a cross section of the types of insulation material available for retrofitters and new builders.

• Blankets and rigid boards with or without kraft paper/aluminium foil vapor barriers- (e.g. Fibreglass wool, rock wool, slag wool etc)
• Batts of Insulation -(e.g. Fibreglass, mineral wools etc)
• Loose Fill insulation – (e.g. Fibreglass wool, slag wool, rock wool, cellulosic material such as recycled paper, cotton wool, vermiculite etc.)
• Sprayed foams – (e.g, Polyurethane foams, expanded polystyrene foam etc.)
• Reflective Insulation and radiant barriers– (e.g. stand alone kraft paper backed aluminium foil or plain aluminium foil etc.)

Structural Building insulations

• Rigid Panels – (e.g. composite Outsulation of EPS with finishes, dry walls etc.)
• Structured Panels (e.g. compressed straw panels etc.)
• Straw bales (e.g. tightly bundled straw finished with masonry plaster)

When you are thinking of building insulation (whether a new construction or a retrofit job) paying careful attention may not be a wasteful exercise. After all proper building insulation may be the difference of up to 30% of your home heating bill. Avoiding thermal bridges (continuous direct paths for heat transfer from indoor to out door) in the building envelope is equally important. As the currently effective HES scheme of SEI reimburses significant amounts against retrofit thermal insulation expenditure it is best to look in to this as well.

What is really the attic in your building?

Attic is defined as the space enclosed by the building wall and is located directly under the roof. As this is an area generally not occupied continuously by anybody (except in special designs and home modifications) it is unheated. Some components of utilities such as water heaters, hot water storages, air conditioning and heating air ducts and also goods storages may be located here depending on the volume of space available. Generally the roof and the floor are insulated though more often than not inadequately.

Areas of heat loss in an attic

Some major points of heat loss have been identified by researchers. For example;

• Roof
• Attic floor
• Air vents
• Attic access
• Poorly erected hot/cold air distribution ducts

and,

• Poor insulation in hot water tanks and plumbing

The silver lining in the whole issue is that of all insulations of an old or new building attic insulation is the easiest to tackle. And in most cases can be carried out by semiskilled amateurs as a DIY project perhaps during a weekend!

Types of attic insulation

Commonly used attic insulations are as follows;

• Cellulose Insulation – loose fill
• Cellulose Insulation – Stabilized Insulation
• Fibreglass and mineral wool Insulation- loose fill
• Fibreglass and mineral wool insulation- batts
• Expanded Polystyrene or Phenolic foam insulation- rigid boards
• Cellular Foam Insulation – sheets of Butyle and Nitrile rubber foam etc.

Tips for DIY enthusiasts

• The use of cellulose insulation is currently gaining grounds over fiberglass and mineral wool insulation. The reasons being none other than economy! The thermal resistance value “R” per unit material cost for cellulose fill is the lowest for any attic insulation.

Further the modernized material does not require a vapor barrier (subject to local building codes permitting it)

• The cellulose loose fill can be filled in between timber joists. This may raise dust posing a health hazard. Adequate precautions are advised. These fibres may settle about 20 % over the time. An overfill of at least this amount is therefore recommended. On the other hand stabilized cellulose material does not show this weakness and is therefore better suited for the job in spite of the higher price.
• On the other hand the EPS, PF and cellular foam slabs can be easily cut to exact size between joist spacing and also can be fitted over them completely eliminating any thermal bridges unlike fiberglass, cellulose material etc.
• Handling of Fibreglass or mineral wool insulation should be done with care. Protective clothing and masks need to be worn.
• Check all hot water plumbing insulation and renew if necessary. Continuous insulation through out is essential. Check near the storage tanks for weak insulation and rectify as needed.
• Hot/cold air ducts are easily neglected items in an unconditioned attic. Poor seals between flanged joints, weak insulation in these places and elsewhere, non continuity in insulation etc. may cause high thermal energy losses.
• Another cause of heat loss from conditioned areas to the attic is the recessed light fittings. Caution should be exercised when insulating the fitting as this will also entrap the heat emitted by the lamp leading to disastrous fires. Seeking manufacturer's instruction is therefore essential in this matter.
• Vent grilles to and unheated attic is essential for proper ventilation of the occupied areas. Special care need to be taken to prevent obstruction of these grilles (generally located at the periphery of the attic floor).

Cavity Walls

Cavity walls are external building walls which incorporate an air gap which may be within the wall structure itself (for e.g. Hollow block walls) or between two solid walls (or between two partitions having a narrow air gap separating them).The latter technique was widely used in houses constructed between 1932 to 1982.

Almost all houses constructed after 1982 adopted the cavity wall technique with or without the use of insulation.

Why do you need insulation in cavity wall?

The wall cavity maintains an air gap which is a good insulation. (In fact it is about the best available conveniently and almost all other manufactured insulation material incorporates air bubbles or spaces in order to gain this advantage).When the cavity width between the two walls exceed a certain critical dimension the air within the gap start moving about due to convection (convection currents) which start assisting heat transfer from the warmer to the colder side rather than blocking it.

Porous insulation fill will restrict the air movement within the cavity providing optimized insulation quality.

How to find out whether your house has cavity walls

All houses built during the last 25 years are almost certain to have cavity walls. It is possible these may be insulated too. Houses built during the 50 years prior to that are also likely to have cavity walls but may not have any insulation.

A sure giveaway sign is the brick pattern of the exterior wall. In general wall bricks are laid in 3 patterns. viz;

• Stretcher bond
• Flemish bond

And,

• English bond

Of these only the stretcher bond patterned brick walls will have a wall cavity. A stretcher bond patterned brick wall will have the bricks laid flat on side and in a linear manner i.e. bricks laid end to end.

Another tell tale sign is the width of the total wall. Due to the incorporated cavity the width is in excess of the normal 300 mm width you would expect it to have.

It is always better to get a skilled person with proper tools to give advice on these matters. Normally they drill holes in the wall and collect data to find out the details of the air gap, insulation material (if any), and the present condition of it.

Types of insulation for cavity walls

The commonly used materials are;

• Fibreglass or mineral wool with short strands
• Cellulose loose fill or stabilized cellulose

• Phenolic and other Synthetic foam cavity board –(Used in new constructions only).

Cavity wall insulation if it is a retrofit in an existing house will not take more than 3 or 4 hours. Of course it has to be handled by a skilled person with specialized tools. They would drill holes in the existing external wall at regular intervals, insert a special nozzle and blow short strands of insulation material in to the wall cavity. If the house is being constructed anew phenolic foam rigid board or expanded polystyrene foam boards too may be used.

•  The distribution of warmth (the heat energy) is from the floor level upwards

•  The wall or ceiling mounted heat emitters are eliminated

•  The heat distribution is uniform through out the space and cold pockets are thus eliminated

Types of UFH systems

There are two main types of under floor heating technologies depending on the source of heat. i.e.

•  Electrical heater element type (in cable or mat form)

And,

•  Warm water circulating pipe type (hydronic)

Under different situations and requirements each type has its own applications.

Which is suitable for my home?

Examples of situations where electrical heater elements are better suited are;

•  When the subfloor is already high to embed a piped system

•  In an existing building where the finished floor level does not permit raising further to embed pipes

•  When cheap or excess electrical energy is available in the building (say for example through solar PV panels or wind turbines)

•  When a high back pressure rated warm water circulating pump (necessary for hydronic systems) cannot be incorporated in the system.

On the other hand the embedded pipe system is better suited for you when:

•  Cheap warm water is available from your existing or retrofitted hot water boiler.

•  When zoning and a condensing boiler is used in your home heating system.

•  In geothermal heat pump installations

•  When adequate clearance is available above sub floor to embed the heater piping.

•  When solar water heating is available

•  When better energy economy is sought

What ever is your choice, under floor heating (UFH) provides you with individual room temperature control, avoid obtrusive and ungainly terminal heating equipment and affords much less maintenance.

Consider these well in advance!

Some important points to keep in your mind when considering a UFH system are;

•  A particular product is designed for a specific type of installation and therefore the manufacturers' guidance must be sought and adhered to. For example pipes suited for screed embedded UFH is not suited generally in under wooden floor installations and vise versa.

•  Whether it is a solid or wooden floor the under side of the heaters must be well insulated with an adequate layer of insulation and also reflective insulation foil doubling as a vapor barrier to prevent condensation (if a damp proof membrane is not available below subfloor).

•  If your building exists and is with solid floors the pipe or the mat is generally laid on the floor and finished with timber, laminate or any other type of tiles. The level of the finished floor will be raised .This will in turn necessitate the lifting of the doors, skirting boards etc.

•  In the case of electrical heating elements you will find heating mat (which is in effect heater elements attached to a flexible mat) can be laid on the surface rather than embedding in the screed. This has the added advantage of maintaining the element/cable spacing for uniform heat distribution.

•  In tiled floors the heater elements or the pipes may be embedded in the adhesive which is generally flexible.

•  Suspended wooden floors pose a different situation altogether. Generally the pipes or cables may be mounted between joists (clipped or clamped to under side) with adequate insulation and foil vapor barrier below. All joints must be well sealed with sealant tape. Though views may differ on timber floor insulation, as moisture is detrimental to timber (which is a good insulator but absorbs moisture easily) a vapor sealant and insulation (depending on the floor design “U” value) is prudent. Further it should not be forgotten that the timber floor will be exposed to two different temperatures on either side which may warp the material unless adequately insulated.

•  Another technique used to suspend pipes or cables under timber floors is to lay a masonry filling under the timer work embedding the heaters. This is however slow and labor intensive process and accordingly expensive. The masonry filler will be heavy too and unless you are sure of the floor strength this method is not advisable.

•  The third method for timber floors is to fix an aluminium plate to support the heater elements from under .This is tedious and costly in terms of material as well as labor.

Evaluation of all pros and cons for the type of installation best suited for your application and the purse is a must prior to finalization. Another aspect you must consider is whether your new under floor heating installation will qualify for any SEI grant aid schemes.

John Mahoney is a freelance author who writes about various Renewable Energy topics including UnderFloor Heating. For more info contact him at http://www.techstore.ie/Renewable-Energy/Underfloor-Heating.html

Source: http://www.articletrader.com ]]>