Limitations on window size & location in a new design is directly impacted by rules outlined in the building code. In many cases, the number and size of these windows can be automatically cut in half due to a fire response time supplied to an authority having jurisdiction by the fire houses in a given area. The magic number is 10 minutes. If a fire department reports that their response time would be outside of this number if a fire were to occur in your location, this could really affect your design and/or cost to build. Half the allowable windows is substantial. Installing a fire suppression system in a home is an option to allow for greater windows, but this adds cost. When choosing a lot to build on, or if you plan to purchase a home and renovations are required, it may be a good idea to ask your realtor about the response time of the local fire department and how this might affect your plans to build or make improvements. Additionally, a consult with a local building design firm or the authority having jurisdiction may help ensure you are fully aware of what design restrictions may exist with respect to your lot.