"Help with the heat", as in preventing it from getting too hot, or as in keeping it warm enough? I think if you plant next to anything solid, it will heat up in the sunlight, and radiate that heat back at the plant when the sun goes down. But yes, a white house will absorb less sunlight. If the house is on the north side of the bed, the reflection off the white house will certainly give the bed a little more sunlight than it would have otherwise.

Perfect! The house is on the North side and painted a very pale mint green! Nancy

Assuming you are planting far enough away from the house to walk in between the house and vegetable plants, the effects from house reflections will be minimal.

Actually, the amount of extra light you get on the plant will depend on the solid angle subtended by the wall. In plain language, that means that if you were sitting where the plant would be, how much of the sky is covered by the illuminated wall. If half the sky is covered by the wall, and the paint is optimally reflective, you'll get quite a bit of light off of it. But yes, if the plant is far enough away from the wall that the wall covers only a small fraction of the sky (as in, a plant that is ten feet away from a ten foot wide and high wall), the effect will be smaller.

And x=z627squared.....Actually the plants should be about 2-3 feet from the house. If that helps. Nancy