Looking for Moisture: Inspection of a Tourist Village at the South of Spain

Rafael Royo Carla Montagud ITC Spain, Universidad Politécnica de Valencia

ABSTRACT

Results from a thermal inspection in a tourist destination in the south of Spain are presented in this report. The high presence of moisture alerted villagers to the need of an assessment. The inspection shows different typical kinds of building failure: the effect of impressive thermal bridges, non-uniform insulation layers, water infiltration...even broken water lines!

TECHNICAL EQUIPMENT

The results of this report were obtained by means of an analysis of the thermal and visual images taken by a S65 ThermaCAM infrared camera from FLIR Systems AB.

The inspection work was carried out by PH. D. Rafael Royo Pastor, Level III thermographer (ITC Boston), responsible for ITC (Infrared Training Center) Spain, with a wide experience in infrared thermography.

A BRIEF INTRODUCTION TO BUILDING THERMOGRAPHY

Infrared thermography gives the building inspectors an advantage over other technologies when studying the structure and maintenance work in buildings. Using Infrared Thermography will make it possible to detect immediately different building failures such as thermal bridges, water infiltration, condensations…etc. Infrared Thermography is a very important tool for detecting water infiltration in terraces and roofs in United States. This practice is commonly called ‘roofing’.

There are many applications where thermal thermography is really helpful, for instance:

PREVIOUS RESULTS, OBJECTIVES AND METHODOLOGY

The objective of the present inspection is to determine the reason for the moisture and water infiltration detected at several houses in a tourist village in the South of Spain. A view of the village can be observed in the following picture.

A view of the village.

The typically mild weather of this part of the Spanish coast may have led the builders to believe that there was no need for insulation materials, because the temperatures are warm, even in the winter. As we will see, this is not a good choice, even in such mild weather!

Previous to this study, different maintenance and repair work had been developed during more than ten years, but in most of the cases, problems arose again. Before inspecting the houses with the infrared camera, a powerful heating system of the domestic type, such as electrical convectors or gas heaters, was turned on to improve the thermal contrast. This is fundamental for the infrared inspection of buildings, where the thermal differences may not actually be very high. It is important to keep in mind that temperature differences are always necessary for infrared images; otherwise, a uniform radiation image would be obtained! In one instance, the terrace at the top of the house was flooded to check for possible external water infiltration.

DETAILED DESCRIPTION OF THE INSPECTION RESULTS THERMAL BRIDGES:

The actual designs of walls and roofs often incorporate elements with higher thermal conductivity, and therefore lower conduction resistance than the rest of the main structure. In general, this type of element is thermally critical. High conduction heat transfer takes place across these high-conductivity structural elements, even if the rest of the construction was perfectly isolated with low conductivity materials. In this report, these elements are referred to as "thermal bridges”.

The high thermal conductivity of a thermal bridge lowers the overall thermal insulation of the structure, and therefore increases its U-value, (heat transfer overall coefficient). This results in an increase of the heat transfer across the thermal bridge. Increased heat transfer across the thermal bridge has a number of effects. In wintry conditions with internal heating in the building, the internal side of the thermal bridge becomes cooler, giving rise to the term “cold bridge”. Such cold bridges result in increased condensation risk and mold growth on the internal surrounding surfaces. In summery conditions with refrigeration inside the building, the opposite effect is obtained, and in that way we could talk (although it is not very common) about “hot bridges”.

Examples of these thermal bridges could be:

The phenomenon of condensation takes place when the moist air temperature reaches the dew-point. The dew-point is defined as the temperature at which the partial pressure of water vapor is equal to the saturated vapor pressure of water at that temperature.

The dew point of moist air can also be described as the temperature up to which the air must be cooled at a constant barometric pressure, in order to condense the water vapor. That is to say, at temperatures below the dew point, any water vapor present in the moist air condenses.

As explained above, thermal bridges become cold zones in winter conditions. This is why condensation occurs in places like corners and wall junctions.

Figure 1. Example of one of the “huge” cold bridges detected.

The enclosed pictures show some cases where these phenomena take place: Figure 1 represents one of the most common problems at the houses in the village.

As shown in Figure 1, there are some impressive thermal bridges in the building’s structure, located mainly in beams and pillars. This problem takes place when the internal surface temperatures are lower than the condensation value or dew point.

As described previously, the dew point is the maximum temperature of a surface for which condensation of water vapor in the air is produced. Its value depends mainly on air dry temperature and the relative humidity. As both parameters increase, the dew point will be higher as well.

It is difficult to estimate the exact position for these condensation phenomena, which depend on:

Condensation is evident in many places in the infrared and visual images which are shown at the following pages.

Figure 2. Example of condensation phenomenon due to thermal bridges.

Figure 3. Example of condensation phenomenon caused by thermal bridges.

Figures 2 and 3 show some huge “cold” bridges where condensation is clearly visible. Such impressive cold surfaces come from the effect of the metallic structure of the building and the fact that there is no insulation of any type. As shown in the previous figures, the beams of the building’s structure are perfectly visualized and their surface might be condensation sources, mainly in the intersection line with the vertical wall. Air is still at these locations. In these circumstances, condensation is highly probable. There is no possible partial repair for this problem, because condensation will appear again in the next and closest cold place.

Figure 4. Example of a thermal bridge located at the pillar.

Figure 5. Example of a thermal bridge located at the pillar.

Figure 6. Example of a thermal bridge located at corners and beams.

Figures 4 and 5 show how the whole height of this pillar may cause for condensation and mold growth. At the house shown in Figure 6, it is important to point out that the owner normally uses a strong gas heating device which increases both temperature and absolute humidity. These features make condensation even more likely. Our inspection, indicated two very important problems. The first problem is the same as the one in the previous house: very cold beams and vertical pillars, even more obvious than for the first case.

Furthermore, there is obvious moisture in Figure 7. We believe this is from the condensation effect itself, and not from external water infiltration. In this image, the shape of the bricks in the wall can also be distinguished, due to a global insulation failure.

Figure 7. Example of very cold surfaces causing condensation from global insulation failure.

Figure 8. Example of a thermal bridge located at corners and junctions of walls and the ceiling.

In Figure 8, the thermal bridge extended through the internal side of the cabinet, without any obstacle from the wood frame. At first sight, this might seem strange, but it is reasonable because the effect comes from the cold surface of the contour walls in the house. Some moisture at the corners due to the condensation of water on the surface is also evident.

INSULATION FAILURE:

Insulation failure is a very common problem in buildings nowadays. In many situations, builders aim to save as much money as possible, reducing the quality and also the quantity of the materials used in the construction. Because of this, there are many cases where insulation of the external surface and the walls of many buildings are not designed appropriately.

Figure 9. Example of a hot area caused by insulation failure in a non-habited house.

Figure 9 shows an uninhabited house. There are some hot areas present at the top of the wall. This is due to the powerful heating used at the adjacent house. It is important to note that, previous to the study, the owners of the houses were asked to turn on the heating system and set it to maximum capacity, to improve the thermal contrast, mainly at the common beams. We can conclude from Figure 9 that there was a global failure in the insulation of the walls.

A more detailed examination helped locate some strange thermal patterns at the ceiling surface, which are shown in the following thermal images. The reason for these suspicious thermal patterns is non-uniform insulation or the use of different material layers at the internal side of roofs or terraces. This could be the origin of the described water infiltration. These thermal discontinuities are more easily observed in Figures 10 to 12, where it is even possible to distinguish the shapes of bricks or blocks. Non-present insulation or broken water proof layers could be the reason for the moisture caused by water infiltration on the external side of the building.

WATER INFILTRATION

It is critically important to manage moisture infiltration in buildings. Water damaged building materials and furnishings, if not appropriately handled, can become significant sources of microbiological contamination in building environments and lead to health problems for occupants. During their lifetime all buildings will have some kind of water problem. Appropriate management of these water problems to reduce microbial growth will ensure that any health risk to building occupants is minimized.

Water coming from the rain or dew is suitable to infiltrate through the structure of the building. When this water evaporates, a large amount of energy is absorbed by the water and taken from the wet surface. This can cause cold zones.

The following thermal images reveal a noticeable cold zone at the surface of the terrace. However, this cold zone could also be a reflection of the “cold infrared radiation” coming from the clear sky. As the boundary of the cold zone is not just the contour of the solar shadow, and considering the low temperature levels achieved, we can assume that there is a cooling evaporation effect from condensation or previous infiltration. Moreover, if these failures are associated with non-uniform wall layers, they could become an additional cause of moisture infiltration.

Figure 14 shows the terrace, which is a feature of the very top surface of the house. An extended cold zone was detected, close to the drain, showing the effect of accumulated water. This may be the reason for so many moist spots on the bottom of this building’s roof. Figures 13 and 14, include the different materials used in the construction of the floor. As the infrared radiation of an object depends on its material, the temperatures of each material shown by the infrared camera are different.

EVEN LEAKAGE OF WATER IN PIPES!

In the last house inspected, the owner complained about moisture and mold growth in the walls. Just by taking a quick shot with the infrared camera, the problem was easily to visualize. A strange “yellow and blue” vertical thermal pattern appears on the wall above the door frame: there are hot and cold long things inside the wall!

Afterwards, we entered the room behind the wall. “Oh, it is curious, it is the washing room!” At the end, the reason for the problem was evident. When we focus the camera at the same wall from the other side…

There are two different taps. Water lines are shown clearly in Figure 16. The surface around one of them presents a higher temperature than the other. We can see that the cold zone has its origin in the tap, around which there is a noticeable temperature gradient.

It is important to point out that even if the pipes were not broken, water coming from the condensation of water vapor in the air could appear on the surface of the cold water pipe!

SUMMARY

REFERENCES

Frank P. Incropera and David P. DeWitt ; “Heat Transfer Fundamentals”; School of Mechanical Engineering Purdue University; Prentice Hall, México, 1999

A. F. Mills; “Heat and Mass Transfer”; University of California at Los Angeles; IRWIN, 1995 Bynum, Richard; “Insulation Handbook”; McGraw-Hill; New York, 2001 Lstiburek, Joseph and John Carmody; “Moisture Control Handbook”; Van Nostrand Reinhold; New York, 1993

ACKNOWLEDGEMENTS

The authors would like to thank Jorge Payá for his help in checking this report.

ABOUT THE AUTHORS

Rafael Royo is Professor Titular of the Universidad Politécnica de Valencia. He has developed a variety of research and development projects for important automotive manufacturing companies, including Renault and Volkswagen. He is a Level III Certified Infrared Thermographer and Instructor from ITC Sweden. He has written several Inframation papers.

Carla Montagud is an Industrial Engineer, specialist in Thermal and Hydraulic Energy. She’s working in the IMST-GROUP in the Universidad Politécnica de Valencia.