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Guide to the insulation of buildings

Energy sources are always more rare and expensive, their unregulated use, unfortunately has led to some phenomena of environmental pollution and global heating which each of us know. The way for a sustainable management of the buildings in which we live is necessarily the improvement of their energy performance: let’s see what are the strategies for the thermal insulation and legislative aspects.

Why heating consumption must be reduced

Until a few years ago, during the building design the question of the environmental impact and energy saving were not considered. Above all before the Law n. 10 of 1991(“Rules for the application of the National Energy Plan on the rational use of energy, energy conservation and development of renewable sources of energy“) and, worse, before the L. 373 of 1976 (“Rules for the management of energy conservation for thermal use in building“) dispersing huses were built, they were poorly insulated and with inefficient heating systems. The great availability of energy at low prices, which has been a feature of the past decades, did not represent an impulse to save.

Today, instead, we all are aware of the influence of the energy bill on the family budget, and that the supply of fossil energy sources (oil, natural gas) is not to take for granted. The price increase of the crude until 150$/bbl in the summer of 2008 and international crises concerning the gas pipelines are two examples of the general uncertainty in this field. They are non-renewable energy source, and therefore it appears evident that it is necessary more austerity in consumption.

At the same time, a new awareness is developing. More consumption means greater impacts on environment: remember that, for example, 25% of the emissions of carbon dioxine in Italy is produced by domestic heating installations. And that, about one third of the national energy demand is represented by the consumption of the residential construction (source: ENEA).

Houses built during the last years are compulsorily designed for the energy saving, but some improvement actions can be made on less recent buildings. There are many tax incentives (governmental al local) which allow to improve at lower price the energy efficiency in our houses.

Thermal insulation means to ensure a constant saving secured by management costs by the time. If it is made with expertise, indeed, actions and solutions used can last even more than fifty years. Actions are usually amortised in few years, and they are efficiency both in winter and summer in keeping the temperature of the internal environment.

Thermal insulation

Heating (or cooling) a thermally poorly insulated house means trying to fill a holed bucket (or, in worse case, a colander). The management of poorly insulated buildings is considerably expansive from an economic point of view: its efficiency is really limited. Remember that, for example, in a thermally non-insulated cottage, heat losses can be great: about 30% of energy can be lost through the roof, 20% through the windows, 30% through the walls. In condominiums, the situation is not better: losses can also reach 65% due to windows and walls. The use of effective insulation systems can drastically reduce these dispersion, by halving or still reducing it up to one tenth.

Insulated materials are materials which are able to reduce the thermal dispersion in efficient way. These are porous substances, with cavities in order to retain little air bubbles and so reduce the thermal exchanges between the internal and external part of the building. Insulpolystyreneated materials are sold in panels, mats, bulk or foamed; the most used are polystyrene, polyethyleneor polyurethane expanded, fibers


of wood, hemp or polyester, expanded cork, glass wool.

The capacity of insulation depends on the thichness with which it is placed, as well as the kind of employed material. According to estimations, each square metre of insulation avoids the production of CO2 as a forest of about 150 square meters can absorb!


External walls, coatings, floor

Insulation actions of the external walls can be realized in three ways:

  • from outside or “coating”: a layer of insulating boards is positioned on the external walls, and then it is covered by marters or plasters;
  • from inside: some insulator layers are added from inside, and this is an operation necessary for buildings with architectural or artistic value facades, which cannot be modified by a coating system. However, this provokes a less internal habitability and it obliges to recollocate radiator, sockets, etc.;
  • In cavities: if there is an empty space in the walls, this can be filled with dissolved insulator materials, liquid (that then solidify) or by stiff plates.

As you have already seen, the loss of heat from the roof can provoke an important thermal dispersion of a building, but problems do not miss, even during the summer: the poor insulation causes the excessive hotness of the houses. The solutions can be adopted on all kinds of coatings: flat ones (that is to say terrace have to be sealed and paved) and inclined. In the case of non-habitable attics, it is convenient to place the insulators on the floor: in this way you will avoid to heat useless. For habitable attics as mansards, the insulation is made along the inclined walls, or eventually from outside in order to avoid to reduce excessively the habitable space.

Finally, floors and garages and cellars which do not need to be heated must be insulates, or when the house is built on an arcade.

Each time that there is an action of insulation in buildings, it is necessary to eventually analyze and withdraw heaters and air-conditioning, in order to have excellent inside temperatures.


Who must intervene

If your house has been built after the 2006, it must respect the current law (L. 10/1991, D.Lgs. 192/2005) about the containment of energy consumption: therefore, you are safe for the thermal insulation. This means that your house presents limited dispersions of heat during the winter and recesses (that is to say heat that enters) during the summer; moreover, walls are well thermally insulated and they favour the enter of the solar energy in winter months, while they repair during the summer; moreover, the house is equipped with efficient heaters and air-conditioning.

Houses built between the 1991 and 2006 did not conform to the legislation on the containing of the energy consumption (L. 10/1991), that has been perfectioned in the mean time: therefore, even if we are talking about recent houses, some improving actions can be taken in order to optimize the energy performance.

For houses built before the 1991 it is essential to intervene in order to reduce energy consumption: at that time it did not exist a specific housing legislation, therefore it can be done a lot in order to increase the efficiency of the building.

When the owners will intervene on their houses, they will be able to reduce costs for the building: a direct advantage if you live in the same property, but also an indirect one. Efficient buildings have a higher value from an energy point of view, both on the property and lease market. Anyone who lives in a condominium with central heating is aware of the energy waste: central floors are usually overheated during the winter in order to ensure an acceptable temperature to the “marginal” floors. In this way, waste is very huge, but there are some ways to save. For example, each apartment could be equipped of its own system of regulation and accounting of heat.

According to the Law n. 192 of 2005, moreover, in case of maintenance and extraordinary restructuring of building, the owner must adopt thermal insulating measures of roofs, walls and windows.

The Financial asset foresees some incentives for interventions for the energy conservation of own house up to December 2010. Thermal insulation of walls and coatings, as well as infix and frames, foresees deductions of the 55% until 60.000 euros, which can be recovered within five years. Besides, there are some discounts up to 7000 euros for purchase of buildings with low energy impact: the entity of the funding depends on the saving and the respect for environment. If you want to use these incentives, it is better to act directly: unlike the past, this funding is limited to 420 million euros, shared with other kinds of incentive (domestic appliances purchase, mopeds, ecc.).


“Do it Yourself” insulation treatments

You do not need to contact some specialised companies in order to start to thermally insulate your house: there are some easy measures and actions which are accessible to everyone.

First let’s have a look at our windows, through which most of the internal heat wasted outside (about 20%) and that, vice versa, during the summer insinuates in buildings. If windows are single-glazing, you need to replace them as soon as possible with double-glazing windows. They have, as the name suggests, a double-glass-surface in which there is an air space which thermally insulates. Double-glazing system can reduce the external noise. On these surfaces, can be also applied a reflecting film which avoids the passage of heat, it avoids the entering of the ultraviolet radiation in the house and – why not – it also protects our privacy.

Frames too deserve our attention: the traditional “draughts” represent a great source of thermal dispersion. If frames are particularly old, it is better to evaluate their replacement; Alternatively, you need to well control the maintaining of the seals, and if it is necessary, you need to replace them. The most immediate intervention is represented by the application of insulation strips and silicone in the points in which there are draughts, but, in case of excessive losses, it is recommended to replace the infix.

A significant thermal dispersion also occurs in the shutters boxes. Usually these are non insulated structures which, being in contact with the outside world, they represent a potential escape route of the inside heat. They can be insulated in a very easy way, with insulating panels or with the use of stripes against the draughts.

Towards the future: the passive house

This kind of house is absolutely revolutionary, as it removes an important component: the “conventional”heating based on boilers and radiators. The heating system of this buildings is ensured by solar radiations, which gears some photovoltaic panels; there are also heat pumps which allow the heating through a ventilation system.

How do these installations work? They are simply based on the recovery of thermal energy in the air which is in the house. Let’s imagine to change the air during the winter: by opening the windows, there is an exit of hot air and entering of cold one. Then, it must be led to the inside temperature. On the contrary, the controlled-ventialtion at energy recovery ensures that the outgoing hot air gives its heat to the entering cold one, by reducing the energy required for the heating. During the summer it occurs the opposite phenomenon: the outside hot air necessary for the replacement is partially cooled by the outgoing air. During this process, these two kinds of air do not mix.

Other heating sources are that generated by the working of the domestic appliances and by the presence of the tenants of the house: thanks to a very efficient system of insulating thermal system, these heat sources can practically compensate the losses towards the outside during the cold periods!

In case of cloudy periods, there is the possibility to produce electricity through geoexchange installations (by using the geothermal heat) or through little wind blades.

Materials with which a passive house is built, provide a high degree of thermal insulation: in this way, heat losses are reduced and an independent house is obtained from an energy point of view.

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