Kenneth J. Gadsby

Comparison of natural and forced ventilation for radon mitigation in houses

Radon mitigation by natural basement ventilation was compared to mitigation by forced ventilation (pressurization) and to mitigation by the operation of a modified heating and air conditioning (HAC) system in a series of experiments conducted during the spring and summer in a research house. Both natural ventilation and basement pressurization reduced average basement radon concentrations from 800 Bq m−3 to less than 150 Bq m−3. Natural ventilation reduced radon levels both by dilution and by decreasing basement depressurization and thus the radon entry rate. Basement pressurization reduced radon levels by increasing ventilation and lowering subslab radon levels, but is significantly more difficult to implement than natural ventilation. The operation of the forced air HAC system with a duct that supplied additional outside air to the return side did not reduce indoor radon concentrations. These experiments have clearly demonstrated the relationship between the outdoor-basement pressure differential and the radon entry rate, ventilation rate, and radon levels.

Use of natural basement ventilation to control radon in single family dwellings

Abstract Natural basement ventilation has always been recommended as a means of reducing radon levels in houses. However, its efficacy has never been documented. In these experiments, natural ventilation has for the first time been studied systematically in two research houses during both the summer cooling season and the winter heating season. Ventilation rates, environmental and house operating parameters, as well as radon levels, have been monitored. It can be definitively concluded from radon entry rate calculations that natural ventilation can reduce radon levels two ways. The first is by simple dilution. The second is by reducing basement depressurization and thus the amount of radon-contaminated soil gas drawn into the structure. Therefore, basement ventilation can be an effective mitigation strategy under some circumstances. It might be especially useful in houses with low radon concentrations (of the order of 370 Bq m −1) or those with low levels and which cannot be mitigated cost-effectively with conventional technology.

Isolating The Building Thermal Envelope

The evaluation of the thermal integrity of building envelopes by infrared scanning tech-niques is often hampered in mild weather because temperature differentials across the envelope are small. Combining the infrared scanning with positive or negative building pressures, induced by a blower door or the building ventilation system, considerably extends the periods during which meaningful diagnostics can be conducted. Although missing or poorly installed insulation may lead to a substantial energy penalty, it is the search for air leakage sites that often has the largest potential for energy savings. Infrared inspection of the attic floor with air forced from the occupied space through ceiling by-passes, and inspecting the interior of the building when outside air is being sucked through the envelope reveals unexpected leakage sites. Portability of the diagnostic equipment is essential in these surveys which may include access into some tight spaces. A catalog of bypass heat losses that have been detected in residential housing using the combined infrared pressure differential technique is included to point out the wide variety of leakage sites which may compromise the benefits of thermal insulation and allow excessive air infiltration. Detection and suppression of such leaks should be key items in any building energy audit program. Where a calibrated blower door is used to pressurize or evacuate the house, the leakage rate can be quantified and an excessively tight house recognized. Houses that are too tight may be improved with a minimal energy penalty by forced ventilation,preferably with a heat recuperator and/or by providing combustion air directly to the furnace.

Use Of Thermography In The Diagnostics Of Energy Use In Multifamily Dwellings.

Rising energy costs have placed a heavy burden on multifamily complex managers in recent years. To reduce energy expenditures these managers are then faced with making difficult decisions as to which building retrofits will prove to be most cost-effective. The Building Energy Research Group at Princeton University has embarked on the development of analysis procedures that will provide these managers with a prioritized list of energy conservation opportunities (ECOs). The case studies presented here illustrate the importance of thermography in this analysis procedure, its impact on the inspection time, and the value of the information gained. The infrared scan often eliminates large areas of the thermal envelope from further inspection and aids the analyst in locating energy losses through construction that would otherwise be difficult to find. Not only does thermography guide us in the choice of ECOs but it also provides us with information that should lead to the construction of better buildings in the future.

Year-Round Use Of Thermography In House Doctoring

There have been many presentations of thermographic residential building analyses at the past ThermosInse conferences. A number of these papers have dealt with evaluation of insulation voids and more recently a few have described air leakage detection 2,3 during the colder winter months. This paper will focus on the thermographic application in the House Doctor instrumented energy analysis approach as developed by Princeton University. The central theme will be the application to a year-round research or commercial activity. Some of the conditions that could create thermographic problems, as well as techniques that may be used to lessen these difficulties, thereby extending the thermographic season is discussed. Our experiences in summer thermography with and without the use of a building pressurization system is also covered.