A statistical measurement of how an individual score relates to the mean (average value) in a group of scores. A Z-score of 0 means the score is the same as the mean (average value). A Z-score can be positive or negative, indicating whether it is above or below the mean and by how many standard deviations.  

Zero carbon homes

The zero carbon homes standard is a Government policy which will require house builders to decrease all carbon emissions from energy arising from fixed heating and lighting, hot water and other fixed building services (eg ventilation) in new homes from 2016. It does not include carbon emissions from appliances or ‘white goods’. See consultation from 2014