I just ordered 3 All-Star spotlights. They will be used as uplighting for the front of my 2-story house. My question is, how bright should the LED bulb be? 5w? 6w? 7? And is there a big difference in color temperature between 2700k and 3000k? Thanks in advance!
Nice choice with the All-Stars! Brightness (or more accurately - light- or lumen-level) is determined by wattage (as you point out) and by beam spread. The wider the beam spread, the less bright the illumination will appear. Let's say, we're just looking at 60º lamps. And, your house face has white aluminum shingles. The light color and high reflectance of the illuminated siding indicate that you should use a minimal wattage lamp - such as a 3W or (at most) a 5W. If your siding is darker or has lower reflectance (such as red brick or dark weathered shingles) then light will be greatly absorbed and you may need a 7W lamp. I'm a fan of using minimal light levels since the overall effect is more subtle and less distracting. I only using higher perceived brightness when increased safety or security is required. Regarding color temp, the difference in color temperature between 2700K and 3000K is noticeable only when you a have a mixture of color temperatures in a scene. For example, if lights are on inside a house, these will typically be somewhere between 2000K and 2700K. That light will project into your outdoor space and become part of your lighting scene. If, in this case, you use 2700K landscape lights then the outdoor lights will more closely match the light emanating from the windows. And, conversely, if you are inside the house and look outside, the light color will more closely match your indoor environment. If you use 3000K for your outdoor lights, then the mixed scene (indoor and outdoor) will result in the outdoor light looking far bluer than the indoor light. Some people prefer this distinct color difference and point out that plants may actually look a little better under 3000K. But, there is a widely-held opinion that warmer (more yellow) light is perceived as more welcoming than bluer light. For this reason, I prefer sticking to 2700K in most outdoor lighting scenes. By the way, if you disregard the indoor lighting contribution and are just comparing 2700K and 3000K lights side-by-side, yes you will see the difference - and you will prefer one over the other.
As someone who despises the sickly cool lighting I'll say the difference between 3k and 2700k is minimal, but noticeable to a keen eye. It's funny, because I've found that people are usually in one camp or the other. The wife likes the hideous blue (4-5k) light temperature, but I buy the bulbs so 2700k it is.
