Sorry not my area - but here are a quick few. hopefully they help
http://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm
http://www.h-mac.com/heat-load-calculator/heat-load-calculator.php
http://www.acca.org/speedsheet/
http://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm
http://www.h-mac.com/heat-load-calculator/heat-load-calculator.php
http://www.acca.org/speedsheet/