Minnesota’s New Energy Code Requires Today’s Buildings Meet Stricter Standards
By Jeffrey R. Kemp, P.E., LEED AP
Mechanical and Electrical Systems Manager, Kraus-Anderson Construction Company
Reprinted with permission from The Duluth Chamber’s The Duluthian magazine.
Buildings designed and constructed under Minnesota’s updated energy code are expected to be more energy efficient than those built under prior standards.
Minnesota adopted new energy standards published by the International Code Council and the American Society of Heating, Refrigerating and Air-Conditioning Engineers. The standards were developed with a goal of reducing energy consumption by 30% compared with a similar building constructed a decade earlier.
The updated requirements affect the building envelope, heating and cooling, lighting, power systems and commissioning. While these changes can increase initial construction costs, they can also reduce long-term utility expenses.
Building Envelope Requirements in Northern Minnesota
Northern Minnesota is in the coldest climate zone in the United States. The updated standards increased roof and wall insulation requirements by more than 50%. As a result, new buildings may include one-and-a-half times the insulation used in buildings constructed under previous requirements.
The standards also limit glazing to 40% of wall area and require a continuous air barrier to improve building airtightness.
At project completion, blower-door testing verifies that the building meets air-tightness criteria. The test involves removing an exterior door and placing a fan in the opening to create negative pressure inside the building. The test measures the air drawn through the fan. If the building does not meet the required leakage criteria, additional sealing or rework of exterior-wall systems may be necessary before it passes.
More Efficient Heating, Cooling and Ventilation
Heating and cooling systems are required to be more efficient, use improved controls and undergo commissioning. Equipment manufacturers have generally kept pace with the new requirements by improving performance to meet higher efficiency standards.
The updated code also includes requirements for demand-controlled ventilation and energy-recovery ventilation.
Demand-controlled ventilation is used in densely occupied spaces with periodic use, such as training rooms and conference rooms. Carbon dioxide sensors measure occupancy conditions and increase fresh-air ventilation when carbon dioxide levels rise.
Energy-recovery ventilation captures energy from exhaust air, such as air removed from kitchens and restrooms, and uses a heat exchanger to help condition incoming outdoor ventilation air.
Lighting and Power Controls
Power and lighting systems are affected in similar ways.
Lighting power densities have been reduced, and modern LED lighting systems have lowered lighting-power requirements by more than 40% during the previous decade.
New lighting-control requirements include occupancy sensors that turn lights on and off when people enter or leave spaces, plus daylighting controls that reduce lighting output when daylight is available.
Under the ASHRAE standard, power to 50% of receptacles in office areas must also be controlled with occupancy sensors.
Updated standards increased insulation requirements for projects in northern Minnesota. Construction at Lake Vermilion State Park, Minnesota.
Commissioning and Long-Term Value
The updated code includes commissioning requirements for energy systems. Owners typically retain an independent commissioning provider to functionally test heating, cooling, ventilation, power and lighting systems and confirm they perform as designed.
The commissioning provider completes testing and prepares a report that may be requested by the building-code official. Depending on system complexity, this service may cost between 0.25% and 0.65% of total construction cost.
While stricter energy standards can affect a building’s initial cost, sometimes by as much as 5%, many industry professionals expect the measures to pay for themselves in fewer than 20 years. That can result in a return on investment exceeding 5%.
The standards also help utility companies plan for future demand by improving their ability to forecast energy consumption for buildings expected to come online in the years ahead.
Learn more about Minnesota energy code requirements, Part 1, Minnesota energy code requirements, Part 2, mechanical, electrical and plumbing services and building science services.
CATEGORY: Construction