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Energy conservation programs have made matters worse 'In addition to the tightening of buildings and sealing windows, building managers have shut down ventilation and air conditioning systems at night and on weekends in an ef fort to lower energy costs. When HVAC systems are shut down condensation builds up and settles inside the ductwork. If dirt is present in damp ductwork spores and microbes can flourish, only to spread through the building once the system is turned on again in the morning. A further cause of sick buildings is the recirculation of indoor air in a sealed system, at the expense of fresh outdoor air. In such a system there is continuous redistribution of infectious microbes, allergenic dusts and spores. In 35% of the buildings we have studied we found the fresh air dampers completely closed. All of these buildings were operating with 100% recycled indoor air' states Gray Robertson. '80$ of indoor pollution problems can be eliminated. In our experience of more than 40 million square feet of building studies we have found that there are three major contributors to poor indoor air. 1. Poor ventilation Inadequate ventilation 64% Zero fresh air intake 35% ~ 2: Poor filtration Inefficient air filters 57% 3. Dirt in ventilation systems Contaminated air handlers 63% Contaminated ductwork 38% By improving ventilation rates, upgrading filters and cleaning up the air handling system we can eliminate over 80% of indoor pollution problems. Such changes will improve worker productivity, enhance staff morale and reduce absenteeism.

COMPARATIVE STUDIES E It is interesting to compare the results of a ACVA study of two buildings in Sweden. Alviks Strand building Air condition and HiRoss sub-f loor ventilation system system Air distribution Excellent, even distribution throughout all areas Flexibility Excellent, easy to accommodate modifications in office layout Hygiene Excellent system. Very easy to clean without specialist techniques. All areas very accessible. AIR QUALITY READINGS recently conducted Conventional building Conventional HVAC system Poor, considerable short-circuiting of air from air supply to return Poor, significant expenditures required if office layout changed Good, but future problem of cleaning inaccessible duct- work. Alviks Strand Conventional Airborne dusts over 0.5 121,300 344,500 micron dia. per cubic foot of air. C02 content 463 ppm 680 pp CO content S02 3 ppm <0.1 4 ppm <0.1 NO ox <0.2 <0.2 N Cn 0 Ozone <0.05 <0.05 ~ Airborne microbes 66 units/m3 158 units/m3 .A N ~ ~ Nicotine content w Adjacent to smoke generating machine 50 ug/m3 60 ug/m3 4

In next room to s smoking machine 2.3 ug/m3 3.17 ug/m3 Key: C02 = Carbon dioxide CO - Carbon monoxide S02 = Sulphur dioxide NO ox = oxides of nitrogen ppm = parts per million ug/m = micrograms per cubic meter OBSERVATIONS Although one' comparative study is not sufficient for scientific purposes there is considerable evidence that the Alviks Strand building, using the HiRoss sub-floor ventilation system as compared with a conventional system, provides: 1. Improved air distribution 2. Greater flexibility 3. Better ventilation with improved air exchange as evidenced by lower carbon dioxide levels. 4. Cleaner air with lower dust counts 5. Better accessibility for routine maintenance and cleaning.