Blower Door testing XXL, Energy efficiency, Thermographic surveys, GPR concrete scaning. Thermographic surveys use infrared thermal imaging techniques to reveal heat losses. Sources of heat loss are thus made visible, giving a valuable insight into the weak spots of your building. The Blower-Door test measures the airtightness of a building or part of a building. This standardised test is used to determine how many times per hour the volume of air in the building is renewed for a given pressure difference relative to the air outside.