In what's been a busy month for architectural competitions, the Royal Institute of British Architects (RIBA) has revealed its Manser Medal longlist. Since 2001, the Manser Medal has been awarded annually to RIBA's favorite new UK-based house or extension. The shortlist will be announced September 4, and the overall winner declared during RIBA's Stirling Prize ceremony, on October 16.

Last year's Manser Medal winner was the Slip House, by Carl Turner Architects, and this year's crop is no less impressive, with 28 new homes hailing from England, Wales, Scotland, and Northern Ireland making the grade. Here's our pick of the five standout designs.

Tree House, by 6a Architects

6a Architects extended this London-based home in order to offer its disabled occupant more mobility, as the original home was very difficult to navigate by wheelchair.

The firm designed a simple single-story extension that makes each of the public rooms and the principal bedroom in the main house easily accessible. Sporting low ceilings and a minimal footprint, it takes its place alongside the listed home uncommonly well for a modern extension.

Stormy Castle, by Loyn and Co Architects

Based in the Gower peninsula, within one of Wales' five officially-designated areas of outstanding beauty, Stormy Castle also rests close to the remains of an ancient Celtic hill fort.

The modern residence blends nicely into the ancient landscape, thanks in part to Loyn and Co's decision to retain and integrate an old barn and school house that already lay on the site. The home is also partly sunken into the ground and features sustainable technology in the form of photovoltaic solar panels, ground source heat pump and rainwater harvesting.

Treetops, by Howarth Litchfield Partnership

The Treetops project saw Howarth Litchfield Partnership renovate an existing and rather tired-looking two story detached house in North East England which dates back to 1964, into a modern and energy-efficient home for an architect and his wife.

Located atop a steep hill, the house was completely transformed in appearance and given new insulation, energy-efficient windows, and sustainable tech such as ground source heating and solar panels. Thanks to its modern makeover, the house now operates off-the-grid.

House Number 7, by Denizen Works

Situated on the Isle of Tiree, which is the most westerly of Scotland's Inner Hebrides islands, House Number 7 is the result of an overhaul of an old stone cottage plus the addition of two large extensions.

The original cottage now serves as a guest house, while the large extension is the main home. The extension looks a little like a modern agricultural shed, or similar industrial unit, and could very easily have clashed horribly with the existing cottage. However, Denizen Works managed to pull it off and has enjoyed admiring words from critics since, making House Number 7 a strong contender to win later this year.

Loughloughan Barn, by McGarry-Moon Architects Ltd

The Northern Ireland-based Loughloughan Barn features the renovation of a typical stone barn in Broughshane, County Antrim.

McGarry-Moon Architects retained the existing basic rough-cut stone structure and original openings, adding a large modern roof made from zinc, copper, timber and glass. The firm also cantilevered the main living space, and the end result looks excellent.

Head to the gallery for a look at the other entries.

Source: RIBA