Energy efficiency: the envelope first

The building envelope is the shell: walls, roof, floor, windows and doors. Improving it cuts energy needs for the life of the building, and it comes before choosing equipment. Here is the order that works.

Why the envelope first

Equipment can be replaced in a decade or two, but the envelope stays for generations and is costly to fix later. A better envelope reduces the size of the heating and cooling system needed.

Five parts of the envelope

• Insulation: continuous and correctly placed. See insulation types.
• Air sealing: see air sealing.
• Windows and doors: choose U-factor and solar gain for climate.
• Thermal bridges: steel and concrete conduct heat across insulation.
• Shading and orientation: in hot climates, shade reduces cooling load before any machine runs.

Then ventilation, equipment and lighting

With a good shell, add controlled ventilation, right-sized HVAC and efficient lighting and hot water. See HVAC basics.

Measure what you can

Compare designs using the calculated figures your designer provides, and test airtightness at completion. Use your own utility bills and local energy codes as a reference, not generic claims.

Cost and payback

Payback depends on local energy prices, climate and use, so we do not publish generic numbers. Ask your designer to model options with your inputs.

Quick answers

• What gives the best return? Usually air sealing and insulation done at construction, because adding them later costs more. Check with a model for your case.
• Are high-performance windows worth it? It depends on climate, window area and price. Compare modelled results.
• Do I need an energy rating? Some places require it. Ask your authority.

Keep reading

• Insulation types and where they go
• Air sealing the building envelope
• HVAC basics for small buildings
• Steel frame building envelopes coordination guide

Always check the project drawings and specification, and confirm requirements with the engineer of record and the local authority.

Questions people ask

What gives the best return?

Usually air sealing and insulation done at construction, because adding them later costs more. Check with a model for your case.

Are high-performance windows worth it?

It depends on climate, window area and price. Compare modelled results.

Do I need an energy rating?

Some places require it. Ask your authority.

Sources and further reading

• US Department of Energy, Energy Saver
• International Code Council
• US EPA, Indoor Air Quality

Text Digital Oro

Digital Oro International advertises on The Company Chronicle. This guide was written by our editorial team from public sources and general professional practice; it does not describe a guarantee, quote or offer from Digital Oro International. Confirm current terms, prices and availability with the operator before you decide.