# Decay factor and volatility (2 assets): do you keep simple correlation to calculate vol? or exponentially weighted correlation?

I have calculated exponentially weighted variances (and covariance) for a future and the underlying index.

Now that I have exponentially weighted variances for my 2 assets using a lookback period of 1 year, and knowing that the portfolio of 2 assets volatility depends on the correlation between these 2 assets, do I need to use the simple correlation (simple returns with no decay) or do I need to use the correlation between the new exponentially weighted variances?