You still can get white background and colored buildings using a custom palette as "saturation" of a palette is determined only by its "light" color (i.e. the color of roofs). Example:
<svg width="90px" height="40px" xmlns="http://www.w3.org/2000/svg"> <rect width="90" height="40" id="paper" fill="#ffffff"/> <!-- White background --> <circle cx="20" cy="20" r="10" id="ink" fill="#000000"/> <circle cx="45" cy="20" r="10" id="medium" fill="#336699"/> <circle cx="70" cy="20" r="10" id="light" fill="#ffaa55"/> </svg>