All you need to know about thermal insulation in Spain

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.

Escribir comentario

Comentarios: 20
  • #1

    Henry Morrison (lunes, 12 febrero 2018 12:01)

    I am presently looking into having my house insulated. Can you recommend any companies in the Alicante region.

  • #2

    Juan Pacheco (lunes, 12 febrero 2018 13:13)

    Hi there Henry,
    We know of various companies.
    Can you tell us where about in the Alicante region is the property?

    Thank you

    Juan Pacheco

  • #3

    Alena Daunter (domingo, 06 mayo 2018 09:00)

    Hello, I am looking in to insulating floors and external walls on my property. I live in Almeria region, Cantoria. Can you recommend any companies. Many thanks

  • #4

    Alena Daunter (domingo, 06 mayo 2018 09:10)

    I realized after my first winter how cold it gets, but especially in the house. The heat is escaping I guess from everywhere! I have changed the windows and insulated celings with 4cm blue harden type of polystyrene, I know its not the best to insulate from inside, but taking a roof apart wasn't a option. Now I am thinking about insulating the outside walls of the house and as I would like to change floors for different it would be a great idea to insulate the floors too. Please, could you help me as I can't find much about materials available for the floor insulation.
    many thanks


  • #5

    Roger Osbourn (lunes, 01 octubre 2018 20:44)

    I too are having the same problem as Alena Daunter and am considering the same remedy. I live in Javea, Alicante. Could you please advise.
    Many Thanks

  • #6

    Juan Pacheco (jueves, 11 octubre 2018 19:20)

    Thank you for your comments.
    I will hang up detail drawings on various solutions very soon which will solve your insulations problems that you have requested.
    Juan Pacheco

  • #7

    willi (jueves, 29 noviembre 2018 15:17)

    Dear Juan,
    You mention in your article the following:
    How are we supposing to thermal insulate an existing building?
    Insulation solutions can be done either on the inside, on the outside of the building or by injecting insulation into cavities walls.
    I Have a large crawl space height 160cm to 60cmspace under the house.
    What are the best material to use to insulate this space, as the floor above is always very cold ( floor is tiled.
    Pls advise

  • #8

    Juan Pacheco (miércoles, 12 diciembre 2018 18:02)

    Hi Willi,
    Thank you for reading our blog.
    If you are lucky enough to have this underbuilt space I suggest you use any rockwool panel about 8cm thick which can be fixed onto the soffit of the floor slab.
    I will send you some pictures via your email.


  • #9

    Juan Pacheco (miércoles, 12 diciembre 2018 18:04)

    Hi Willi,

    I have just realized that I don't have your email please send it to arquitectojapm@gmail.com

  • #10

    kate russell (domingo, 06 enero 2019 19:16)

    Hi Juan, please can you advise me. I live in a stone built house, over 100 years old, very cold in winter and very hot in summer, especially the first floor which has a thin beamed ceiling and is warm to touch in summer. I have heard I could have some sort of foam sprayed on the outside of the roof but I don't know if the roof is strong enough to take the weight of an effective layer of foam. Do you know of a company near Orihuela who could help me. I would appreciate any advice you can give me, thank you

  • #11

    Juan Pacheco (lunes, 07 enero 2019 12:48)

    Hi Kate,
    I do not recommend the spray foam on the outside not because of the weight of the actual foam but because of the final aesthetics once applied. I don't think it would look very good.
    I think that there are multiple ways of insulating your house from inside that way you don't have to heat or cool the whole house before you obtain any positive effect. If you had a false ceiling you could introduce fibre glass between the false ceiling and the roof beams ( minimum 8 cm thick)
    If you don't have false ceilings then there is a plaster board that have thermal insulation incorporated on its reverse side, you can fix this plasterboards between the beams.
    These plaster boards can also used for the internal walls.
    Maybe if you send me some photos taken inside and outside I could help you better.
    Send them to info.spanisharchitect.com


  • #12

    Janine (sábado, 20 abril 2019 07:38)

    Hi Juan
    We have a house built in 2005. It has a loft space but no access or insulation. There are cavity walls but no insulation. Internal wall cladding is not possible. We live here year round so really need some insulation. Can you recommend anyone in the Girona area? Thanks!

  • #13

    Juan Pacheco (sábado, 20 abril 2019 12:13)

    Hi Janine,
    Thank you for contacting Pacheco & Asociados Architects.
    I am afraid that I don't know any firm on that area, however. I can recommend what I think are the most appropriate insulation solutions for your house.
    With regards to the loft I do think that fibreglass or rockwool roll type blankets would be the most economical if you can get. For that area and for the roof I would recommend 10cm thick minimum
    The actual specification in Spanish would be:
    "Lana mineral ISOVER IBR constituidos por rollos de lana de vidrio ISOVER, no hidrófilos, revestidos en una de sus caras con un papel Kraft que actúa como barrera de vapor, de 100 mm de espesor cumpliendo la norma UNE EN 13162 Productos Aislantes térmicos para aplicaciones en la edificación con una conductividad térmica de 0,040 W / (m•K), clase de reacción al fuego F y código de designación MW-EN 13162-T2-100 2,50 WS-Z3-AFr5."
    All you need to calculate is the square meters of your roof.

    For the walls if you have a cavity I would tend to go for injected polyurethane and its specification would be:
    "Aislamiento de espuma de poliuretano con conductividad térmica muy baja (0.028 w/m*k). Aplicado mediante inyección"
    Here again you have to calculate the square meters of walls you need to insulate. Normally properties of 2005 would have 4-5cm thick cavity but you need to check that, as the price would change depending on the thickness.
    One thing to note is with this material the cell may be open or closed that will also affect the price.

    I hope that that I have been of help.

  • #14

    Suzanne (domingo, 09 junio 2019 02:10)


    I have had external wall insulation on two properties inEngland and would like to get it done on my house in Spain.
    Could you recommend any installers for the Andalusia/Granada/Córdoba region please?
    Thank you.

  • #15

    Juan Pacheco (miércoles, 12 junio 2019 18:59)

    Hi Suzanne,
    You have selected the best possible insulation that you can have. I recommend that the thickness of the insulation to be at least 8 cm thick better still 10.cm.
    And I am afraid that we don't know any contractors on that area., sorry.

    Juan Pacheco

  • #16

    Martin Coombs (lunes, 12 agosto 2019 13:18)

    Do you have a representative that can visit our property? In Pliego Murcia.


  • #17

    Juan Pacheco (lunes, 12 agosto 2019 15:35)

    Hi Martín,
    Can you explain what services would you require from us?

    Juan Pacheco

  • #18

    Lynne Goodwin (viernes, 10 enero 2020 11:15)

    Hi Juan, we have a semi-detached house in Pilar De La Horadada that was built in 2005/2006.
    Can you recommend companies in this area to advise us on insulation please?

  • #19

    Brett Alderson (miércoles, 14 octubre 2020 10:49)

    I Have a large crawl space height 160cm to 60cmspace under the house.
    What are the best material to use to insulate this space, as the floor above is always very cold ( floor is tiled). could you recommend anyone who can do this in the Javea area ?

  • #20

    Juan Pacheco (jueves, 15 octubre 2020 10:21)

    As it is a space under the floor slab I recommend any material with good "U" value i.e. polyurethane boards or stiff rockwool sheets, minimum 8cm thick as the property is in Javea, These sheets can be adhere to the underfloor slab by using special glue recommended by the manufacturer of the insulation sheets. Depending on the product you choose sometimes it is recommended that the sheets should be fixed by mechanical means. You can find a good range of products in Leroy Merlin and you could fix them yourself. I am afraid that I don't know anyone in Javea that could do this kind of job.

    Juan Pacheco

Al ser imposible conocer en profundidad cada caso, todos los consejos y contestaciones a la preguntas realizadas en este blog, los consejos dados son propiciado en términos generales por lo que se deberá contrastar con el asesoramiento privado de un abogado  y/o un arquitecto para estudiar en profundidad su caso.

As it is impossible to know in detail every case asked in this blog all our replies are given in good faith but we strongly suggest that you obtain private advice from a solicitor /and /or  architect who will be able to study in depth your own particular case.