Having gone through another month of August in Spain I am sure that many readers may have wondered if there are ways of reducing the heat impact in their houses or any method to drop their electricity bill on air conditioning.
Real depredators on energy. Houses can be real depredator on energy; the problem is aggravated if the house in question is built before the 1970´s. I can imagine the temperature inside an old apartment without any insulation whatsoever in let say the centre of Murcia at 3.00pm in mid of August and could easily reach the 40ºC or 104º Fahrenheit.
Keep in mind that the energy consumption of Spanish homes is about 20% of total consumption in the country and in the last 15 years have seen a sustained upward growth. Moreover, Spain has a great dependence on foreign energy 80%, so any energy saving measure would be very beneficial, first, to consumers pocket and, secondly, for the entire economy of the country.
The recent entry into force of Royal Decree 314/2006 of 17 March, approving the new Spanish Building Regulation (CTE) aimed, among other objectives, to reduce energy consumption in buildings through stricter insulation techniques.
The CTE partially introduced the European Directive on Energy Performance of Buildings (2002/91/EC), which obliges member’s states of the European Union by law from October 2006. It is mandatory to insulate the existing buildings above a specified minimum when it is rehabilitated, altered or renovated in more than 25% of its covered area of any building that has a floor space exceeding 1,000 m2.
Consequently as a result of this law, any building over 20 years old which may be under insulated, it is considered desirable to implement a thermal insulation upgrading.
Savings of up to 50%
Up to 50% of the energy consumed for heating and / or cooling could be easily saved. In practice, we must bear in mind that the costs of building work in a dwelling, are attributed to labour costs, and fixed costs so that once you have decided to undertake a rehab of any kind, thermal insulation should be seriously considered even though this may not have been at first the main objective of the rehabilitation.
The immediate question is: What measures can be taken to reduce consumption of energy on these buildings? The answer also is immediate; any works that improves thermal insulation is one of the best measures that any one can undertake. Any action in this regard will produce an immediate savings in energy and therefore immediate saving in money. Don’t forget that thermal insulation is not seen but you can certainly notice it in your pocket.
To insulate a home is to be enabling the external elements of a building increase their resistance to the passage of heat, which is achieved by incorporating insulating materials on: exterior walls, roofs, floors, walls and voids.
If you repair it, insulate it
So it would be a good idea to take advantage when a roof is repaired to introduce thermal insulation, or perhaps when pipes are replaced to insulate the new lay out. If replacing the external windows choose them double glazed, it all redound in future energy saving. Normally the investment in thermal insulation can be amortized within 5 to 7 years on most construction elements and the life of a new building it is expected to last for at least 100 years so you can see that the money saving could be substantial during that period if you are still around to see it!!
The incorporation of thermal insulation not only contributes to save money as we have seen but also improves our home in other aspects:
Improve the comfort and well being for the user: Housing which is thermally insulated contributes to the welfare of the users by maintaining a comfort temperature inside the house, in winter and summer. Your family will notice it.
It will also help to reduce the emissions of gases (Mainly CO2) from boilers using gas, petrol or coal. Also electricity production is associated with CO2 emissions.
It will also eliminate condensation and improve sound insulation: on one side we are removing indoor humidity which often lead to mould growth and also reduces the noise from the outside or from the neighbours
Adding value to the building: the advantages described may be used as positive arguments for the rental or sale of the property. All new built homes must have an energy certificate to identify the property with an energy saving rating, so that you will know in advance how much energy your home is suppose to require.
How are we supposing to thermal insulate an existing building?
In principle, any existing building can be thermal insulated, although it is necessary to specifically study each case to assess the technical advantages and disadvantages and the cost involve.
Insulation solutions can be done either on the inside, on the outside of the building or by injecting insulation into cavities walls.
Here is an example of how to introduce thermal insulation in a rehab job complying with the new Código Técnico de la Edificación (CTE) of 2007 New Spanish Building Regulations.
Once you have decided to carry out a rehabilitation job, if you are not absolutely certain about what you are doing, the best advice is to contact a professional and insist that his/her solution should comply with the Código Técnico de la Edificación (CTE).
Do contact you Autonomous Authorities and local Town Hall, as it is very possible that there may be an economic aid program for energy saving projects. These programs are held annually, with very short periods for applications to be made, so it is important to be informed and acting promptly.
The MITyC-IDEA, is the Action Plan and Energy Efficiency Savings 2008-2012 and includes a strategic move aimed at improving the standard insulation for homes.
Do contact 2 or 3 companies at least
It is best to contact your local architect or surveyors that may offer independent advice on the feasibility of the various proposed solution, and provide you with an estimate of the savings obtained and a rough estimate of the final price.
Then do contact 2 or 3 companies at least to obtain estimates from, but making sure that the offers do include the involvement of all the necessary trades and when the finished job is handed over all work are integrated in the price given.
A practical case
Let’s take an example of a hypothetical community of neighbours in the city of Madrid, (I have chosen a place with good low temperatures in winter and hot temperatures in summer for the sake of this example) consisting of 6 houses in a building block. The majority of owners decide in one of their annual General Meetings to improve the insulation of exterior walls.
The building was built in 1975 and is, therefore, is more than 30 years old, which means that during its construction no thermal insulation was placed into the cavity walls.
The president of the community obtains professional advice from an architect who decides that the best solution will be to insulate the external walls from the outside as the work will not interfere with the life of owners who don’t need to abandon their houses during the work.
Once the tender documents are prepared they are sent to three rehab companies and one is selected to carry out the works. The building works are done from the exterior with the aid of scaffolding allowing the staff direct access to work from the street.
Another solution it could have been to inject polyurethane foam into the cavity from outside, but the architect wanted to add an additional protection to the external wall.
The reduction of our heating requirements could be cut into half
The building has the following features:
From the CTE we find that the Location is under a D3 climate zone, characterized by a harsh winter and quite hot summers. Albacete, Ciudad Real, Guadalajara, Lérida and Zaragoza are under the same climate zone.
Type of building: single housing block, 3 floors plus a ground floor, with 2 apartments per floor and 12 metres high. The surface of each house is 92 m2, and the glass surface of 10 m2 per dwelling.
The facade is a rendered brick wall and has an approximate area of 1,000 m2.
Assuming that there are 6 apartments in the building, the total surface of the housing facade is approximately about 100 m2, as it has an inner courtyard.
The heating system is that of a natural gas boiler works for 5 months a year, from November to March. In the building there is no installation of air conditioning, which does not mean that cooling is required in the warmer months. In fact, some users have installed small self-contained air conditioning in the lounge and master bedroom, which has not been taken into account in this study.
The annual energy demand, due only to heating, is 132 KWh/m2 per year or, a gas bill of about 895 € per dwelling.
The recommendation from the architect was to carry out a treatment on the four walls of building block incorporating insulation on the outside and a ceramic cladding on the external skin. The cladding would be fixed to the brick by metal anchor points at a distance not more than 80 cm between them.
The existing building is composed of the following skins going from outside to inside.
11,5cmm hollow brick rendered outside followed by a 4 cm cavity (No insulation) a 4 cm hollow brick and 1,5 cm of plaster inside. The thermal transmittance of the entire closure is “U” = 1.83 (W/m2.K). The thermal transmittance (“U” value) indicates the "ease" with which the heat escapes from a home. High values of “U” indicate bad insulation and lower “U” values indicate insulation.
We have added to this a 1cm of ceramic cladding and 5 to 6cm of thermal insulation with Thermal Resistance of 1,5 m2 K/w providing us with a thermal transmittance of all the enclosure of an “U” = 0.55 (W/m2.K) against the “U” = 1.83 (W/m2.K) obtained from our initial wall.
The result is a new facade which has managed to increase its thermal capability in 70% and the impact on the reduction of our heating requirements is approximately 35%.
Therefore, changing from a yearly expenditure on heating of 895 Euros to 585 Euros, this means an annual savings per household of 310 Euros.