Nestled at the top of a quiet and conveniently located cul-de-sac, this oasis is a 5 bed/3.5 bath 3,237 finished square-foot home that has been expanded and made fully green. Set on .20-acre lot with large fenced-in yard with extensive perennial plantings and a lockable shed, the original mid-century home was built in 1959 by Clarke, Raleigh and Cushing Daniels of Standard Properties, which developed Rock Creek Palisades. The split-level design features walls of glass and front-gabled asymmetrical roof-line, a popular mid-century style. The three-level addition, clad in Hardie fiber cement siding, was designed by Robert Smith of Design One Studio.The home was specifically renovated and expanded to be energy efficient and a healthy environment with extensive insulation and double-pane, insulated glass throughout the entire house, and solar tubes to let in additional light. It is perfect for working at home with multiple office areas and is wired for fiber optics, Cat5 and phone. The house features a whole-house air filtration & Energy Recovery Ventilation system, which captures temperature and a portion of the moisture from the stale, outgoing air and transfers it to the incoming fresh air. In addition to having an energy transfer rating of 98% ASE, the system moderates indoor humidity in the winter and turns away outdoor humidity in the summer. Filtration is 95% at 1.8 microns (MERV 12). The house also has a complete water filtration system.The main level of the four-level home incudes the kitchen-dining and living room with cathedral ceilings walls of glass, skylights and original hardwood floors. The open kitchen features stainless steel appliances, quartz countertops and mid-century appropriate cork flooring. The dining area opens to the multi-tiered deck via a wall of sliding glass doors.The second level includes a refreshed full hall bathroom with a soaking tub, convenient laundry room and four bedrooms, including a second large master with ensuite bathroom, double closets and small balcony. The top level of the addition is a private master suite with sitting area, bamboo flooring, custom walk-in closet with extensive built-in drawers and a large bathroom with double sinks and a separate soaking tub. The lower-level features an expansive den with fuel efficient fireplace with two internal fans and ceramic tile flooring and a formal dining area with cypress floors. This level includes a half bathroom plumbed for a full bath. It also has extensive storage space including a separate pantry, a mud room, an Elfa wood coat closet, a workshop and a 519-square foot crawl space/storage space. The family room is wired for 5 channel surround sound.The landscaped lot has a fully-fenced backyard, a shed for additional storage and a parking pad for one car with easy parking in the cul-de-sac for additional vehicles. Flowering perennials include peonies, rhododendrons, gardenias, azaleas, oak leaf hydrangeas, day lilies, mountain laurels, bleeding hearts, tulips and daffodils.Located just north of the Beltway, the home is close to the shops, restaurants and MARC in Kensington, the Wheaton and Grosvenor Metro stations and downtown Bethesda, including NIH and the Walter Reed Medical Center. The house is close to a variety of groceries, including Whole Foods, Safeway and Balduccis. It is near several community pools and only three blocks from Rock Creek Park with its popular cycling/running trail and playgrounds along Beach Drive.