I have silkies in every color they come in plus a few more. I also have bantam Mille Fleur and Birchen Cochins and LF BBS Cochins.
I do not use heat lamps but instead use DLM for my coops and ventilation in the right places.
My roosts are not in the way of drafts coming from ventilation nor are they above nesting boxes.
I use plastic tubs with lids and a hole cut out for nesting boxes in each of my breeder pens. The girls love them and they can get in with their chicks and stay nice and toasty and I can lift the lid off to get at eggs.
The DLM also provides heat from the natural way it decomposes waste material.
Most people don't realize that your chickens put off 10 watts of heat per chicken so that as long as you don't keep two chickens in a huge barn they can pretty well heat the area they are in. I do use heated flat back water buckets though. Combined with chicken bodies, the waterers and the DLM my chickens stay warm even in 15 below temps.
In the summer I take the sides down on the coop for extra air conditioning and I have spinning ventilators on the roofs. Very cheap way to circulate air in the coops.
It does get hot though so I do feed frozen fruit and veggies and put frozen quarts of water in their water buckets.
What do you do for your chickens in the winter and summer months?