Economic Comparison of White, Green and Black Roofs (image) DOE/Lawrence Berkeley National Laboratory Share Print E-Mail Caption The costs and benefits difference stack that has the highest net present value shows the roof type that is most cost-effective. Parentheses around dollar values indicate negative values. Credit Lawrence Berkeley National Laboratory Usage Restrictions credit Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.