Reprinted with permission of The Duluth Chamber’s The Duluthian magazine.
Buildings designed and built this year will be more energy efficient than ever due to Minnesota’s new energy code. Last summer, Minnesota adopted new energy standards published by the International Code Council and American Society of Heating, Refrigerating and Air-Conditioning Engineers. These standards were developed with the goal of saving 30% of the energy consumed by a building today versus the same building built a decade ago. The new standards include significant changes to everything from the building envelope to heating and cooling and lighting and power systems. These changes will increase the cost of building today but also save money for years to come through reduced energy bills.
The northern half of Minnesota is in the coldest climate zone in the U.S. Here, the new standards increased the requirements for roof and wall insulation by over 50%, meaning new buildings contain one and one-half times the amount of insulation as those built previously. New standards also limit the amount of glass a building can have to 40% of the wall area and require a continuous air barrier to make the building air tight. In addition to this, what is called blower door testing is done at the end of the project to prove that the building meets the criteria for tightness. This involves removing an exterior door and placing a fan in the door opening to put the inside of the building under a negative pressure and measuring air that is drawn through the fan. If the leakage criteria is not met, additional sealing or rework of the exterior wall systems is required until the building passes the test.
Heating and cooling systems are required to be more efficient, have better controls, and be commissioned. For the most part, equipment manufacturers are keeping pace with the new codes by improving performance to meet new efficiency standards. New requirements for Demand Controlled and Energy Recovery Ventilation have gone into effect. Demand controlled ventilation is used in densely populated spaces that are periodically occupied, for instance, training and conference rooms. Carbon dioxide sensors are placed in these spaces and more ventilation (fresh air brought into the space) is provided when the carbon dioxide level goes up. Energy recovery ventilation involves capturing energy from exhaust air (from places like Kitchens and Restrooms) and using a heat exchanger to treat the incoming fresh ventilation air from the outside.
Power and lighting systems are impacted in much the same way as heating and cooling. Lighting power densities have been reduced. Most modern lighting systems utilize LED lighting which have reduced lighting power requirements by over 40% in the past decade. New lighting control standards include occupancy sensors to turn lights on and off when occupants enter and leave spaces and automatic daylighting controls to reduce lighting in response to available daylight into a space. In addition to this, under the ASHRAE standard, power to 50% of the receptacles in office areas are also required to be controlled with occupancy sensors.
Commissioning of the energy systems is also included in the new code. The owner will typically hire an independent commissioning firm to come in and functionally test the energy consuming systems (heating, cooling, ventilation, power, and lighting) to ensure that they are performing as designed. The commissioning firm completes the tests and files a report which may be requested by the building code official. The cost for this service can range from 0.25% to 0.65% of the total construction cost depending on the complexity of the systems.
While these new stricter energy standards will have an impact on a Building’s first cost, many argue as much as 5% in some cases, most agree that these measures will pay for themselves in less than 20 years, resulting in a better than a 5% return on investment. Additionally, these new standards help utility companies plan for future demand as they can more accurately predict energy consumption for buildings planned to come on line in the next few years.