Energy Efficiency in Traditional Buildings - Dublin City Council

More documents

Recommendations

Info

ENERGY EFFICIENCY IN TRADITIONAL BUILDINGS A medieval tower house with thick stone walls and a high thermal mass (above) and an unusual lightweight timber building with low thermal mass (below) 21
ENERGY EFFICIENCY IN TRADITIONAL BUILDINGS Assessment methods There are a number of non-destructive techniques available to assess the energy efficiency of an existing building. These range from the use of simple handheld devices such as moisture meters and borescopes to more complex and expensive methods such as thermal imaging. Expert knowledge and experience will be needed to decide which assessment method is appropriate in a particular case, to undertake the assessment and to interpret the results. THERMOGRAPHY Thermography, or thermal imaging, is photography using a camera that captures infra-red (IR) light rather than the visible light captured by a standard camera. IR light occurs beyond the red end of the visible light spectrum and is invisible to the naked eye. All objects that are warmer than absolute zero (-273°C) emit IR light. The warmer the object is, the more IR light it emits. IR cameras record the amount of IR light emitted by an object and translate it into a temperature which is indicated on a scale bar adjacent to the thermal image or thermogram. Even very small temperature differences, as low as 0.1°C, can be recorded by IR cameras. The image produced by an IR camera is multicoloured with each colour representing a different temperature. Different colour scales can be used depending on the objects photographed. Thermography has many varied applications in different disciplines and can be a useful tool when assessing the condition of a building. It has particular advantages for investigating historic buildings as it is a non-invasive, non-destructive method. - 9.0 - 8.5 - 8.0 - 7.5 - 7.0 - 6.5 - 5.9 - 5.4 - 4.9 - 4.4 - 3.9 o C A thermographic image of a double-glazed door at semi-basement level in a nineteenth-century terraced house; note how the yellow patches at the base of the wall, which are damper, indicate that these areas are emitting heat at a higher rate than the rest of the wall Thermal imaging can be used to identify potential problems with a building’s fabric. When looking at traditional buildings, thermal imaging might be used to identify areas of dampness and to locate thinner depths of wall, cracking and voids. Expertise is required both in deciding how and when to take IR images and later in interpreting the information. For example, objects which have high or low emissivity such as metal do not give an accurate temperature reading. Weather conditions, orientation and the time of day when the image was taken all have the potential to affect the reading. The information gathered from thermal images can be properly assessed only in conjunction with data gathered as part of a comprehensive condition survey. AIR-PRESSURE TESTING Air-pressure testing, or fan-pressurisation testing, assesses the air-tightness of a building and the rate of air leakage occurring through the fabric. Modern building methods seek to ‘build tight and ventilate right.’ However, as discussed elsewhere in this booklet, this maxim is not appropriate for traditional buildings which require relatively high levels of natural ventilation to keep the building fabric in good condition. Nonetheless, testing a building’s airtightness may highlight areas or points of particularly high air leakage which could be remedied without compromising the health of the building fabric. Care should be taken when undertaking air-pressure tests on older buildings which contain fragile building elements, including delicate glazing bars and thin, hand-made panes of glass which would be damaged if subjected to excessive pressure. ENDOSCOPY OR REMOTE VISUAL INSPECTION Inspections of concealed parts of a building’s construction can be carried out using a borescope or fibrescope, generally with minimal disruption to the building. This type of inspection can be used to investigate walls, roofs and floors for hidden defects by inserting a borescope or fibrescope into a small inspection hole. In the interior of a protected structure, the drilling of an inspection hole should be carried out with care and a location chosen that avoids any adverse impacts. In some cases, drilling through the building fabric may be unacceptable. 22
Page 1 and 2: advice series energy IN TRADITIONAL
Page 3 and 4: DUBLIN PUBLISHED BY THE STATIONERY
Page 5 and 6: ENERGY EFFICIENCY IN TRADITIONAL BU
Page 21: ENERGY EFFICIENCY IN TRADITIONAL BU
Page 73 and 74:
ENERGY EFFICIENCY IN TRADITIONAL BU
show all

Energy Efficiency in Traditional Buildings - Dublin City Council

Create successful ePaper yourself

Delete template?

Save as template?