Developing energy-loss test techniques for large buildings.

Studies have noted that the concentration of carbon dioxide in the atmosphere has risen by more than a third since the Industrial Revolution and is now rising faster than ever before. During the 20th Century there was an observed global mean temperature rise of around 0.6 °C. Analysis of these two coinciding events has resulted in the now widely accepted theory of "the greenhouse effect". In 1997 the UK Government signed up to the Kyoto Treaty. This stipulated that all ratified states would enter an agreement to either curb, or reduce their total CO2 emissions, depending on the country's current output. Building energy use currently accounts for 46% of total UK energy consumption, resulting in the annual release of 66 million tonnes of carbon into the atmosphere.As one step in addressing this issue the Government introduced the Approved Document Part L2 of the Building Regulations - Conservation of Fuel and Power on the 1st April 2002. A requirement of the document was that a fan pressurisation airtightness performance assessment be made of the completed building envelope. For all non-domestic buildings with a gross floor area of greater than 1000m[2] an air leakage test would be required in accordance with CIBSE TM 23:2000 to prove that the construction was reasonably airtight. The improvements made in the thermal performance of building materials have raised the importance of designing and constructing less air leaky building envelopes. It has been reported that heat loss associated with air leakage could account for 30% of heat loss through the building envelope.It has been noted that previously available fan pressurisation rigs in the UK could not produce the flow rates to attain a satisfactory pressure difference across the envelope for large buildings. 'Large' building tests were previously classed as those carried out on structures with a floor area of up to only 5000m[2]. However, a modem UK warehouses can have a floor area of 60,000m[2] or greater.The thesis provides an account of the origins of airtesting and the evolving airtightness rules and regulations in the UK and other European Union member states. The methodologies for the practical application of airtightness testing and the calculation and interpretation of results are provided. The design, construction and calibration of the largest air testing rig in the UK (and possibly the world) are discussed. Three examples of very large buildings tested using this rig are presented; the largest of which has a floor area of nearly 60,000 m[2]. Analysis of the airtightness test results and practical considerations for testing such large structures are presented. Examples of remedial sealing measures to improve building envelope airtightness performance are presented.The largest building tested was then used as a case study for an investigation into the space heating energy saving benefits of improved building envelope airtightness. Dynamic Thermal Modelling (DTM) and Computational Fluid Dynamics (CFD) simulations were utilised to provide a space heating assessment of the building through a one month period. The study concludes that testing of very large warehouse buildings is practically feasible and that there are considerable energy saving benefits to be had from sealing building envelopes to best practice levels.