above angles appearance building capping cover covered covering edge exhaust-pipes exterior external grooved grooves height high roof roof-area roof-capping roof-whirlybird roofing rooftop shapes sky sunlight sunshine textures tiles tiling turbine-ventilator vent ventilation ventilation-exhaust-pipes ventilation-system ventilator vents whirlybird whirlybirds wind-turbine architectural attached attachments colored colors coloured colours dark edges edging elements light lines perspectives protection protective ridges rows shadows surface surfaces