Solar Design Project_Washington DC

Wardrobe on N » thermal buffer

Rooms with low daylight requirements on N » few openings » minimized heat loss

academic work UCL Solar Design project in Washington DC

2013

The Solar Design project is based on some of the core concepts of the Solar Decathlon, an international collegiate competition run by the National Renewable Energy Laboratory (NREL), US Department of Energy Laboratory.

Evergeen trees and plants » protection from the cold NW prevailing wind

Brief: Design a fully self-sufficient solar-powered house sited in Washington DC, USA. The house is targeted at a young family - 2 children and 2 professional adults one of whom will work at home.

No openings on W facade » protection from the cold NW prevailing wind

Entrance on E » protected from wind and rain

Interior thermall mass walls Deciduous trees »summer shading

Window on E » steady lighting during occupancy hours

Insulated Trombe wall » passive solar system Fully glazed S facade + overhang » seasonal control of solar gains

Site dimensions: 511.0 m² (25.0 m east-west by 20.4 m northsouth) level, unobstructed land.

House size: total building footprint - maximum 74.3 m²; minimum 41.8 m² of conditioned interior space.

Requirements: • Comfort : simulated time-averaged interior dry-bulb temperature of spaces should be between 22.2°C and 24.4°C (72.0°F -76.0°F); • Energy - efficiency : passive solar and energy-efficient design and technologies; • Daylighting: According to the BS 8206 average daylight factor requirements for living rooms (1.5%) kitchens (2%),bedrooms (1%) and office (5%); • “Buildability”:realistic, affordable and convenient construction methods.

South-East perspective rendering. October

Software: AutoCAD, TAS, AGi32, Microsoft Excel, Google SketchUp, Artlantis Studio, Adobe Photoshop, Adobe InDesign,

Weather analysis.

External temperature :

Winter : -3 ÷ 4 ° C (extreme: - 14.7° C);

Summer : 18 ÷ 29 °C (extreme: 36.5° C);

Autumn and Spring : 8 ÷18 °C. External Relative Humidity (RH): average 66%; RH rises to 90% between 19 PM – 10 AM, especially in the summer.

Rainfall, Cloud coverage and Snowfall: cloudy climate; moderate snowfall.

generally humid and

Prevailing wind:

Winter wind : West/North-West- cold and dry wind of high velocity (reaching 55 km/h);

Summer wind : Southern direction- warm, more humid and slow.

Solar gains: Winter: 28 degrees; Summer: 73 degrees;

Architectural and Environmental Concept Ground floor layout • The entrance - on the East, protected from the high velocity cold NW winds and close to the living room, the kitchen, the office and the stairs, to provide easy access to the main spaces.

• Living room / Dining room – South orientation, open to the exterior view and visually connected with the kitchen forming one space. Wall elements are designed to create a semitransparent filter between the main living / din¬ing room space and the kitchen and the office. The ‘double’ height of the space offers a vertical connectivity with the first floor and diffuse light from the upper windows.

• Kitchen - placed on the North, with direct view outside.

The north orientation protects it from overheating during the summer. The heat generated by cooking balances the heat losses during the winter.

• Master bedroom - placed on the North, as it needs little direct light. It is more ‘closed’ and private than the other ground floor spaces. It has no openings towards the west and north, allowing no infiltration from the NW cold prevailing winter winds, and has its own full-height win¬dow-door opening towards the South.

• Office - faces East and can be opened towards the living room area. The east oriented window offers good morning light.

First floor layout • Children Bedrooms - placed on the North side under the reclining roof. The visual contact with the living room space and the roof open¬ings creates a more adventurous and independent environment for the chil-dren, recreating the atmosphere of old fairy-tale attics.

• Stairs - also placed on the north and are lit from above to highlight the vertical movement and maximize the view of the sky.

• Access to the two bedrooms - bridge overlooking the living/dining room.

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Ground Floor AGi32 Lighting Analysis

Ground Floor Plan_1/100

External spaces Three external spaces are formed with different seasonal use and placement: • South-West oriented ‘winter’ yard - high thermal mass floor and sup-porting walls absorb the morning solar radiance and release it in the air during the afternoon, providing a comfortable space for outdoor activities.

• South-East oriented terrace located above the ground floor provides all-year around protection for the office below.

• North-East oriented ‘summer’ yard is designed to be protected from the summer sun and the hot and humid south winds during the summer and hot middle season days.

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First Floor Plan - AGi32 Lighting Analysis

First Floor Plan_1/100

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Environmental Strategy Diagram Sketch_WINTER

Environmental Strategy Diagram Sketch_SUMMER

Trombe Wall Diagram Section_SUMMER

South-East Perspective_ JULY

Trombe Wall Diagram Section_WINTER

South-East Perspective_OCTOBER

South-East Perspective_DECEMBER

Interior Perspective Rendering_Living Room,Trombe Wall

Environmental Strategy: • Well insulated building envelope - heat losses reduction; • Glazed areas on the south façade, properly shaded - increase direct solar gains during cold periods and minimize them during hot periods; • Trombe wall on South façade - increase indirect solar gains; • Minimization of infiltration - through the installation of quality modern openings and well-constructed envelope; • Properly selected vegetation and green roof - optimize the external microclimate; • Use of adequate thermal mass indoors - buffering temperature extremes; • Natural ventilation for cooling during hot periods.

Solar Design Concept: The heart of this house is the double-height living room with a large glazed façade facing South. The roof overhang has been calculated to create the following effects: • Winter - solar heat is drawn through the large glazed façade, retained and re-radiated through the internal thermal mass walls and floor (made of cob). This heat warms the surrounding spaces as well.

• Summer - sun penetration is prevented from heating the façade by the overhang.

Furthermore, by the “Trombé wall” effect, winter sun heat is captured and saved for night time re-radiation in both the living room and the office. In the summer, the glazed layer of the Trombe walls is removed and its inlet apertures are closed. Via the East window of the office cross ventilation is created and the walls perform as external ones.

In the rest of the house, the upper- level windows open and due to the pressure difference, the warm air rises and exits (stack effect ventilation method).

Detail 02_Green Roof_1/10

West Elevation_1/100

Section A-A_1/100

Detail 01_Wall/Floor Junction_1/10

Detail 05_Trombe Wall_1/100

East Elevation_1/100

Materials: • Timber (framework,finish and deck) • Cork (as insulation) • Ceramic tiles (floor) • Pigmented lime plaster (interior rendering) • Cob (clay and aggregates) walls (Trombe, internal thermal mass walls) Section C-C_1/100

Section B-B_1/100

Perspective of South Roof Detail

Interior Perspective_Living Room_Kitchen

North-East Perspective

South Facade Perspective_July

South-West Perspective_July