Probably. The summer light and heat can especially build up. I've got an east facing greenhouse window over my kitchen sink and I had to install the peel and stick vinyl shading to it. Many of my cattleyas got some burn come Spring and Summer. So, I would think your paphs are going to resent it! You may need a curtain for at least the hottest, brightest time of day or the vinyl shading that's available at hardware stores.Is an unshaded east-facing window too strong for paphs? I placed some of my paphs beside it and one opf the new growths on my Fanaticum went limp.