When it comes to environmental building design, one of the more obvious things to consider is size. Large houses require more energy to heat and cool so it follows that smaller houses are by their very nature more environmentally friendly. Also, the larger the building the more materials and energy that will be required for its construction. As a rule, an environmentally friendly building design will be of a size to sufficiently house its occupants and accommodate their activities. What is required is that space be used efficiently, things organized well and possessions kept at a manageable level.