The answer depends on the leak. You may experience a roof leak during a storm, when the wind changes the course of the rainwater and makes it easier for it to infiltrate underneath the shingles. Artificial leaks may also happen if the drainage system (gutters and downspouts) gets clogged and water cannot be directed away from the house properly. But these leaks will disappear as soon as the problem that generates them is solved. In such cases, the roof leak will not affect your heating bill. This will happen only if the problem generating the leak is not fixed, and water infiltration becomes more than a symptom; it becomes a disease that sickens your entire home.
Severe water infiltrations will destroy the protection offered by your attic and wall insulation, and a poorly insulated home will definitely require more air conditioning in the summer and heating in the winter, to maintain adequate and stable thermal comfort. The role of the insulation is precisely to prevent unnecessary air transfer.
Hiring roofers in Dallas to protect your roof is therefore a priority. You must schedule inspections and maintain it periodically, to make sure that any small problem is detected in the right time and not allowed to become chronic.