Insulate existing walls with blow-in or spray foam insulation

Many insulation products can warm up an old house
You can insulate the wall cavities by drilling holes between the studs either from the inside or outside, depending on which surface will be easiest to patch.

Insulation options include fibrous materials, such as fiberglass, cellulose, or rock wool; polyurethane foams; and foamed mineral cement, such as AirKrete.

Foam insulation is inherently more airtight than blown fiberglass or cellulose, but they also more expensive.

Green points

LEED-H Weatherization, as part of a gut rehab project, may make a project eligible to earn LEED for HomesLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. certification. Two key elements required are a quality insulation installation and good air sealing.

NGBSNational Green Building Standard Based on the NAHB Model Green Home Building Guidelines and passed through ANSI. This standard can be applied to both new homes, remodeling projects, and additions. /ICC-700 For remodel points, refer to the ANSIAmerican National Standards Institute. National nonprofit membership organization that coordinates development of national consensus standards. Accreditation by ANSI signifies that the procedures used meet the Institute’s essential requirements for openness, balance, consensus, and due process. standard and follow the appropriate path based on conditioned floor area involved in the remodeling or addition project and the year in which the original home was built.

Learn more in the Green Building Encyclopedia:

ENCLOSURE OVERVIEW
STRUCTURE: EXTERIOR WALLS

From the Green Primer

Is there such a thing as “too tight” or “too much” insulation?