A variant Cel5a endoglucanase has increased thermostability, increased enzymatic activity and/or increased expression in a host, relative to wild type Cel5a. The improved variant Cel5a endoglucanase may be used to hydrolyze more cellulose at a higher temperature for a more efficient and cost-effective production of biofuels as compared to wild type Cel5a. A variant Cel5a endoglucanase is combined with variant Cel6a and variant Cel7a cellobiohydrolases resulting in more effective hydrolysis of cellulose.