San Diego’s office market is being driven almost entirely by expansions from life sciences and technology firms, several of which have signed significant leases in the Del Mar Heights and Carmel Valley areas and near University Town Center in recent months. Venture capital funding is pouring into the region, which has helped fuel those expansions. Leasing volume eclipsed 2.2 million square feet during the third quarter, the highest level in the San Diego office market in 15 years.