The solar house saves energy and insulates, living in harmony with nature

Text and photography by Hu Hsiang-ling

A house is where we settle down and make our home, and it is also an expression of our need for a comfortable life. The appearance of a house shows our imagination of the future, and it is also a facial expression of chasing dreams.

The Solar Library and Energy-Optimized House (Solar LEO House) was donated and built by Mr. Cheng Fu-tien (1948 – 2008), founder of Motech Industries, Inc., in the hometown where he grew up.

Planned by the Hande Institute, designed and supervised by architects Chang Ching-hua and Kuo Ying-chao of Bio Architecture Formosana. With simple design, simple methods and natural materials, passive use of solar energy to save energy, and active use of solar energy through photovoltaics to generate electricity, the Solar Library puts the effective use of solar energy in architecture into practice.

This is a solar house! Mr. Cheng Fu-tien, who donated and built this solar house, hoped: "As soon as people walk in, they will marvel from the bottom of their hearts, 'How comfortable!' It turns out that here in Taiwan, China, we can have a house like this too."

This is a comfortable house! This comfortable solar house has its first floor planned as a 24-hour unmanned library of the Taipei Public Library. In Wanhua District, in this old heart of Taipei steeped in history, we together create a harmonious and safe reading community. The second floor is planned as an energy-optimized exhibition hall, where the project initiator, the Hande Institute, promotes energy education work. Through communication, it puts into practice a new energy life of reconciliation with nature and dialogue with the future.

What is a solar house?

Solar house = active use of solar energy + passive use of solar energy.

Speaking of "solar houses," one always thinks of buildings with solar panels mounted on rooftops in European countries. In fact, a solar house is an architectural design that considers overall energy use and blends with nature. During planning, it makes the most of surrounding natural conditions, such as daylighting and ventilation, and does a good job of insulating the building shell, keeping the interior at a comfortable indoor climate that is ventilated and cool in summer and warm and pleasant in winter, so as to achieve energy savings. Finally, it is paired with renewable energy installations for active power generation, keeping the whole building in a balance of energy and ecology.

The Solar Library is a building constructed with the solar house as its design concept, and the design details are as follows:

(1) Active use of solar energy: photovoltaic system
Without needing conversion through kinetic, thermal or chemical energy, with no chimney, noise or exhaust gas from combustion, the photovoltaic system converts inexhaustible sunlight into elegant and clean electricity. Not only does it generate power. The double-sided light-transmitting "Building Integrated Photovoltaics (BIPV)" system integrated with the building on the east facade of the Solar Library serves as the house's sunshade, so that the solar house not only generates power, but also adds color.

(2) Passive use of solar energy
According to statistics from the Organisation for Economic Co-operation and Development (OECD), more than one third of all primary energy is consumed by air conditioning in buildings. Therefore, considerable energy can be saved through energy-efficient buildings. The overall planning of the Solar Library, combined with appropriate building shell insulation and healthy natural building materials, and at the same time using ventilation and daylighting design, brings in sunlight in winter and blocks heat in summer, making the Solar Library a comfortable and energy-saving "solar house."

1. Building shell insulation
Strengthen roof and wall insulation, using wood fiber boards with excellent insulating properties, to effectively delay and block the influence of outdoor energy on indoor temperature. In addition, it has the functions of sound insulation, reducing the heat radiation effect and maintaining a comfortable, quasi-constant indoor climate. Attention is paid to details at building corners, edges and window connections, fully wrapping the building shell with systematic construction methods, so that the solar house puts on good clothing that is warm in winter and cool in summer. The high-performance wood fiber board insulation system uses waste wood as its production raw material; it is a sustainable building material with no emissions and no pollution, and it has passed fire tests, making it a safe building material that does not catch flame.

2. Air tightness, energy efficiency and sound insulation of doors and windows
Windows are the eyes of a house. Our eyes let us see the world. A house's eyes let us see the house's soul. Argon-filled double-glazed air-tight doors and windows, supplemented by coating technology, reduce to a minimum the impact of heat conduction and heat radiation through door and window glass on room temperature. While bringing green views in and out through the house, they also take into account the needs of insulation and quiet comfort. Wooden window mullions and frames not only blend naturally with the park environment, but also, because their thermal conductivity is lower than the commonly seen aluminum frames, allow the house's overall energy-saving design to be carried through in the details. The air-tight design of the double entrance doors reduces unnecessary heat exchange between indoors and outdoors, keeping the interior warm in winter and cool in summer.

3. Bright daylighting
Natural daylighting reduces unnecessary artificial light sources, not only saving energy but also best meeting the need for comfort. The design of a full row of floor-to-ceiling windows on the south facade of the house maintains good daylighting throughout the four seasons; the window-to-wall ratio on the north facade is reduced to 0.48, using high-daylight windows to enhance the building's overall energy-saving benefits.

4. Air quality and ventilation
We spend more than 90% of our lives indoors, and indoor air quality has a major impact on our physical and mental health. In addition to building code fire safety requirements, in order to achieve the comfort of ventilation and convection, windows on the south and north sides are opened opposite each other for passive ventilation, and air conditioning and ventilation systems are used for forced ventilation.

5. Use of natural paints
Using 100% natural substances of plant and mineral origin as raw materials, rediscovering the relationship between people and nature through the aesthetics of living. Colors from nature are naturally rich. Completely free of chemical solvents and raw materials, it is responsible for the health of both the applier and the user. Natural paint made from gray stone as a raw material is antibacterial and mildew-resistant, preserves the breathability and feel of the substrate, protects the substrate in a natural way, and creates a healthy and comfortable indoor climate. Natural paint is a sustainable building material. From manufacturing, use, to waste disposal caused by leftover material, it is all part of the natural cycle.

Solar house fact file

(1) Area
1. Site area: 246,282 sq m
2. Building area: 440.5 sq m
3. Floor area: 773.3 sq m

(2) Photovoltaic system
1. Existing installed capacity 3.36kWp
Estimated annual power generation 3,300 kWh
2. Planned installed capacity >50kWp
Estimated annual power generation > 50,000 kWh

(3) Wall insulation
1. 15 cm RC + 12 cm thick insulation material (λ value = 0.049 W/mK)
2. Total laid area: 212.19 sq m
3. Insulation material used: 2546.28 cubic m

(4) Door and window daylighting, ventilation and energy efficiency
1. Total window opening area: 269.2 sq m
2. Air exchange rate: forced ventilation, full air exchange in 30 minutes
3. Door and window U value: 1.34 W/m2K

(5) Roof insulation
1. 15 cm RC + 2 layers of 8 cm thick insulation material (λ value = 0.039 W/mK) + 1 layer of 10 cm thick insulation material (λ value = 0.049 W/mK)
2. Total laid area: 407.48 sq m
3. Insulation material used: 10627.48 cubic m