Having spent another month of August in Spain, surely many readers have wondered if there are ways to reduce the thermal impact in their homes or some method to lower the electricity bill in air conditioning, and the answer has a lot to do with thermal insulation of your home
Thermal insulation in buildings
Houses can be a real energy predator; the problem is aggravated if the house in question is built before the 1970s. I can imagine the temperature inside an old flat without any thermal insulation in the centre of Murcia or Alicante city at 3:00 pm in mid-August which could easily reach the 40ºC or 104º Fahrenheit.
It must be taken into account that the energy consumption of Spanish households is around 20% of the total consumption of the country and in the last 15 years it has experienced sustained upward growth. In addition, Spain has a large foreign energy dependency of 80%, so any energy saving measure would be very beneficial, firstly, for the pockets of consumers and, secondly, for the entire economy of the country.
The entry into force of Royal Decree 314/2006, of March 17 which approves the new Building Regulations (CTE), and other stricter additional regulation that have come into effect since that date, had as its objective, among other objectives, to reduce energy consumption in buildings through more efficient thermal insulation techniques.
The CTE partially introduced the European Directive on Energy Efficiency of Buildings (2002/91/CE), which obliges the member states of the European Union by law of October 2006. It is mandatory to insulate existing buildings above a specified minimum when more than 25% of the covered area of any building with a surface area of more than 1,000 m2 is rehabilitated, refurbished or refurbished.
Consequently, as a result of this law, any building over 20 years old that may be under-insulated, it is considered appropriate to implement an improvement in thermal insulation.
Save up to 50% on your electricity bill
In practice, up to 50% of the energy consumed for heating and/or cooling could be easily saved. it must be taken into account that the construction costs of a house are charged to labour costs, and fixed costs, so once it has been decided to undertake a rehabilitation of any type, it is necessary to seriously consider thermal insulation although this may not have been the main objective of the rehabilitation at the time.
The immediate question is: What measures can be taken to reduce energy consumption in these buildings? The response is also immediate; Any work that improves thermal insulation is one of the best measures that anyone can undertake to save money. Any action in this sense will produce immediate energy savings and therefore immediate money savings. Do not forget that the thermal insulation is not visible but you will surely notice it in your pocket.
Insulating a home is allowing the exterior elements of a building to increase their resistance to the passage of heat, which is achieved by incorporating insulating materials in: exterior walls, ceilings, floors, walls and openings.
If you repair it, insulate it
So, it would be a good idea to take advantage when a roof is being repaired to introduce thermal insulation, or perhaps when pipes are changed to insulate the new pipe system. If replacing the exterior windows with double glazing, everything will result in future energy savings. In general, the investment in thermal insulation can pay for itself within 5-7 years for most building elements and the useful life of a new building is expected to last at least 100 years, so you can see that the money savings could be substantial during that time. point if you’re still around to see it!!
The incorporation of thermal insulation not only helps save money, as we have seen, but also improves our home in other aspects:
- Improve the comfort and well-being of the user: Homes with thermal insulation contribute to the well-being of users by maintaining a comfortable temperature inside the home, both in winter and in summer. Your family will notice it.
- It will also help reduce gas emissions (mainly CO2) from boilers that use gas, gasoline or coal. Electricity production is also associated with CO2 emissions.
- It will eliminate condensation and improve acoustic insulation: on the one hand we are eliminating interior humidity that often causes mould growth and also reducing noise from outside or from neighbours.
- It will add value to the building: the advantages described can be used as positive arguments for the rental or sale of the property. All new-build homes must have an energy certificate that identifies the property with an energy saving rating, so that you know in advance how much energy your home is supposed to need.
How are we supposed to thermally insulate an existing building?
In principle, any existing building can be thermally insulated, although it is necessary to study each case specifically to assess the technical advantages and disadvantages and the cost involved.
Thermal insulation solutions can be made inside, outside the building or by injecting insulation into the walls of the cavities.
Below is an example of how to introduce thermal insulation in a rehabilitation work in compliance with the new Technical Building Code (CTE) of 2007 New Spanish Building Regulations.
Once you have decided to carry out a rehabilitation project, if you are not absolutely sure of what you are doing, the best advice is to contact a professional and insist that your solution must comply with the Technical Building Code (CTE).
Contact your Autonomous Authorities and local Town Hall, since it is very possible that there is a financial aid program for energy saving projects. These programs run annually, with very short application deadlines, so it’s important to be informed and act quickly.
Contact 2 or 3 companies at least
It is best to contact your local architect or surveyors who can offer you independent advice on the feasibility of the various proposed solutions and provide you with an estimate of the savings achieved and a rough estimate of the final price.
Then contact at least 2 or 3 companies for quotes, but make sure the bids include all the necessary trades and when the finished job is delivered, all the work is included in the price given.
A practical case
Let’s take as an example a hypothetical community of neighbours in the city of Madrid, (I have chosen a place with good low temperatures in winter and high temperatures in summer for the sake of this example) formed by 6 houses in a block. Most owners decide at one of their Annual General Meetings to improve the insulation of exterior walls.
The building was built in 1975 and is therefore more than 45 years old, which means that during its construction no thermal insulation was placed on the cavity walls.
The president of the community obtains the professional advice of an architect who decides that the best solution will be to insulate the exterior walls from the outside since the work will not interfere with the lives of the owners who do not need to leave their houses during work.
Once the specifications have been prepared, they are sent to three rehabilitation companies and one is selected to carry out the works. Construction work is carried out from the outside with the help of scaffolding that allows staff direct access to the site from the street.
Another solution could have been to inject polyurethane foam into the cavity from the outside, but the architect wanted to add additional protection to the exterior wall.
The reduction in our heating needs could be cut in half.
The building has the following characteristics
From the CTE we find that the Municipality is under a D3 climatic zone, characterized by a harsh winter and quite hot summers. Albacete, Ciudad Real, Guadalajara, Lérida and Zaragoza are under the same climatic zone.
Type of building: block of single-family homes, with 3 floors plus a ground floor, with 2 apartments per floor and 12 meters high. The surface of each dwelling is 92 m2, with the glazed area of 10 m2 per dwelling.
The façade is made of exposed brick and has an approximate area of 1,000 m2.
Assuming that there are 6 apartments in the building, the total area of the house’s facade is approximately 100 m2, since it has an interior patio.
The heating system is that of a natural gas boiler that works for 5 months a year, from November to March. There is no air conditioning installation in the building, which does not mean that cooling is required in the warmer months. In fact, some users have installed small autonomous air conditioners in the living room and the main bedroom, which has not been taken into account in this study.
The annual energy demand, due solely to heating, is 132 KWh/m2 per year, that is, a gas bill of around €895 per home.
The architect’s recommendation was to carry out a treatment on the four block walls incorporating thermal insulation on the exterior and ceramic coating on the exterior skin. The cladding would be fixed to the brick by means of metal anchor points at a distance of no more than 80 cm between them.
The existing building is made up of the following wall layers from outside to the inside
11.5 cm hollow brick on the outside plastered followed by a 4 cm hole (without insulation) 4 cm hollow brick and 1.5 cm plaster on the inside. The thermal transmittance of the entire closure is “U” = 1.83 (W/m2.K). Thermal transmittance (“U” value) indicates the “easiness” with which heat escapes from a home. High values of “U” indicate poor insulation and low values of “U” indicate insulation.
To this we have added 1cm of ceramic cladding and 5 to 6cm of thermal insulation with Thermal Resistance of 1.5 m2 K/w giving us a thermal transmittance of the entire enclosure of a “U” = 0.55 (W/m2. K) compared to “U” = 1.83 (W/m2.K) obtained from our initial wall.
The result is a new facade that has managed to increase its thermal capacity by 70% and the impact in reducing our heating needs is approximately 35%.
Therefore, going from an annual cost in heating of 895 euros to 585 euros, this represents an annual saving per household of 310 euros.