The minimum acceptable level is 0.05 Kw/m. The increase in available heater capacity usually yields better performance and can also make it very difficult for a farm to perform regardless of management practices when the available capacity is below 0.05 Kw/m. Our recommendation would be to install a minimum level of 0.07 Kw/m in new or retro fitted houses and, where external temperatures are frequently below 0 celsius (as in Russia and Canada), the minimum heater capacity should be 0.1 Kw/m