Where Pat is, Tocumwal New South Wales, the climate is dry and hot.. please click link to weather statistics. In Summer, outdoor temperatures averaging 32 deg. C and you can expect it to be 40 to 50 deg. C inside a normal greenhouse. Unless the greenhouse is equipped with proper evaporative cooling system and with huge expense in power costs, such high temperatures will certainly be very damaging to the crops. In the case of the shade house for Pat, it seldom goes more than 1 to 2 degree C above the ambient. All he did was to open both ends of the shade house and let natural air movement to prevent heat build up. As a result, his vegetables thrive right through the year without adverse effects from the extreme heat in Summer and cold in Winter.