We offer customers education about proven energy-efficient technology options, rate information to help them calculate their operating costs, and energy-efficiency programs to meet their goals and needs. In 2018 we invested approximately $9.5 million in conservation programs. We pursued aggressive energy-conservation goals through a portfolio of programs in Minnesota and South Dakota.
Our Minnesota Conservation Improvement Program (CIP) offers customers the opportunity to save energy and money. Our triennial filing, last approved in 2016, established a portfolio of programs and an energy-savings goal of 1.7% of retail sales for 2017-2019. We file an annual update with the Minnesota Public Utilities Commission. In 2018 we filed our 2017 accomplishments, which resulted in a financial incentive of $2.9 million.
In 2018 we invested more than $9 million in CIP and returned more than $35 million in lifetime net benefits to customers. Energy savings reached a record-breaking high for us at 73.3 million annual kWh of energy and more than 28.1 MW of demand. For the year, that is 4.21% of our annual retail sales. At a lifetime cost of less than 1.2 cents per kWh conserved, our energy-efficiency programs continue to be a cost-effective resource for customers.
In addition to designing programs to meet conservation goals, we’re working to ensure savings estimates are measurable and verifiable to meet stringent state program requirements. We highlight below some of the newer programs in our CIP portfolio, which includes more than 30 programs total.
Our South Dakota Energy Efficiency Plan (EEP) continues to encourage residential and business customers to use energy wisely. This conservation plan encourages businesses to install energy-efficient lighting, motors and drives, air-source and geothermal heat pumps, and custom efficiency improvements. The plan urges our residential customers to take advantage of our CoolSavings air-conditioning control program and offers incentives for installing energy-efficient lighting and air-source and geothermal heat pumps.
Results for 2018 show that we invested approximately $493,000, returning more than $2.8 million in lifetime net benefits for customers. Customer energy savings reached 5.3 million kWh, and more than 1.3 MW of demand savings, which was respectively 140% and 127% of our 2018 EEP goals.
Regulatory requirements included completing a triennial program plan, which was filed and approved in 2016. The plan established a new program portfolio and goals for 2017-2019. The 2018 report summarizing 2017 accomplishments was filed on May 1, 2018, and approved on July 3, 2018, resulting in a financial incentive of $134,700.
We continue to voluntarily offer demand-response programs and incentives to our North Dakota customers.
High customer participation in our direct load-control rates makes our company a leader in load management. With one-third of our customers partnering with us in load management, we’re able to curtail a portion of their electrical load during periods of high demand, high energy prices, or system maintenance. Participating customers save on their energy bills with rates that are less than our standard electric rates.
We accredited with the Midcontinent Independent System Operator, Inc. (MISO) a portion of our direct load-control capacity, making it available on a limited basis during MISO system peaks. The amount accredited varies monthly and is set as 90 MW in January, February, and December; 55 MW in March, April, and November; 25 MW in October; 18 MW in June, July, August, and September; and 15 MW in May. Accrediting a portion of the demand resources is a step to further enhance regional transmission reliability.
Our Resource Plan calls for demand-side management resources to increase annually to reach approximately 8 MW of additional summer-season peak-load-reduction capability through 2031. To achieve this, during 2018 we connected an additional 12.7 MW of controlled winter-season load and 3.6 MW of controlled summer-season load.