Building Energy Conservation Topics: Energy-saving Retrofit

1. Material development

(1) External Wall Insulation and Finishing System (EIFS)

The system emerged during the last energy crisis in the late 1970s, and was first used in commercial buildings, followed by civil buildings.

Today, EIFS systems account for 17.0% of commercial building exterior use and 3.5% of civil building exterior use, and use in civil buildings is growing at an annual rate of 17.0% to 18.0%.

This system is a multi-layer composite exterior wall insulation system, which can be applied in both civil and commercial buildings.

The ELFS system consists of the following parts:

The main part is a thermal insulation board made of polystyrene foam plastic, generally 30-120mm thick, which is fixed to the outer wall of the building by synthetic adhesive or mechanical means.

The middle part is a durable, waterproof polymer mortar base, which is mainly used for insulation boards, and is strengthened and transmitted by glass fiber mesh.

The outermost part is a beautiful and durable surface covering.

In order to resist fading and cracking, the coating material generally adopts acrylic copolymer coating technology, which is available in a variety of colors and textures, and has strong durability and corrosion resistance.

(2) Building Thermal Insulation Panel System (SIPS)

This material can be used in civil and commercial buildings and is a high-performance wall, floor and roofing material.

The middle of the board is a sandwich layer of polystyrene foam or polyurethane foam, generally 120-240mm thick, and different flat surface layers can be used on both sides according to needs. For example, in housing construction, both sides can use engineered plywood wood. product.

Buildings built with this material have the characteristics of high strength, good thermal insulation effect, low cost, simple construction, energy saving and environmental protection.

SIPS is generally 1.2m wide and can be up to 8m long. The size is serialized. Many factories can also customize according to the actual size of the project, and supply a complete set. The contractor only needs to assemble on the construction site, which truly realizes residential production. industrialization.

(3) Thermal Insulation Cement Formwork Exterior Wall System (ICFS)

The product is an insulating formwork system, which is mainly made of recycled Styrofoam and cement-like cementitious materials, and is used for cast-in-place concrete walls or foundations.

During construction, horizontal or vertical reinforcement is applied inside the formwork. After the wall is built, the insulating formwork will be used as a part of the permanent wall to form a concrete wall with thermal insulation both outside and inside the wall.

The formwork material outsourced by the concrete wall meets the requirements of thermal insulation, sound insulation and fire protection for the exterior wall of the building.

2. Key points of energy-saving renovation

The overall and external environment design of the building is based on the analysis of the climatic and environmental conditions around the building, through the design of site selection, planning, external environment and body shape orientation, so that the building can obtain a good external microclimate environment and achieve the purpose of energy saving.

(1) Reasonable location selection

The location of the building is mainly determined according to the comprehensive conditions of the local climate, soil quality, water quality, topography and surrounding environmental conditions.

In architectural design, it is necessary to maintain a suitable microclimate environment throughout the entire life cycle of the building to create conditions for building energy conservation, while at the same time not destroying the balance of the overall ecological environment.

(2) Reasonable external environment design

After the building site is determined, its microclimate characteristics should be studied.

According to the needs of building functions, the existing microclimate environment should be improved through reasonable external environment design, and a favorable environment for building energy conservation should be created. The main methods are:

①Arranging trees and vegetation around the building can not only effectively block sandstorms, purify the air, but also shade and reduce noise.

②Create an artificial natural environment, such as setting up water surfaces near the building, using water to balance the ambient temperature, reduce wind and sand, and collect rainwater.

(3) Reasonable planning and body shape design

Reasonable architectural planning and body design can effectively adapt to the harsh microclimate environment.

It includes the determination of the overall volume of the building, the shape of the building and the combination of the building shape, the sunlight and the orientation of the building.

Like the circular plane of the yurt, the conical roof can effectively adapt to the harsh climate of the grassland, reduce the heat dissipation area of the building and resist the wind and sand.

For coastal humid and hot areas, the introduction of natural ventilation is very important for energy saving. In the planning and layout, different air pressures can be formed through the sunny side and shady side of the building, which can form ventilation even when there is no wind, and form a wind tunnel in the design of the building. , so that the natural wind revolves in it to get a good ventilation effect, so as to achieve the purpose of energy saving.

The principle of sunshine and orientation selection is to get enough sunshine in winter and avoid the dominant wind direction, and to use natural ventilation and minimize solar radiation in summer.

However, the orientation and orientation of the building and the design of the general plan of the building should consider many factors. The building is constrained by social and historical culture, terrain, urban planning, roads, environment and other conditions. If the orientation of the building is to meet the requirements of heat protection in summer And winter insulation is often difficult.

Therefore, we can only weigh the pros and cons of various factors, find a balance point, and choose the best orientation and better orientation suitable for the climate environment in this region.

3. Practical cases

Taking Denmark as an example, Copenhagen, the capital of Denmark with nearly 3.84 million inhabitants, plans to become the world’s first carbon-neutral city by 2025.

In August 2012, the City Council adopted the Copenhagen Climate Plan 2025.

When Copenhagen’s net CO2 emissions are zero, the city will be carbon neutral, ie Copenhagen’s carbon emissions are reduced to a minimum.

The remainder is offset by external initiatives, including extensive retrofitting of existing buildings, restructuring of energy supply and transportation modes, etc.

Its maximum allowable energy demand per square meter of heated floor space per year is much lower than in countries such as Sweden, Norway, the United Kingdom, the United States, Germany, and others.

Long-term urban planning has proven to be a powerful driving force behind the development of low-energy buildings in Denmark.

Denmark has a long tradition of urban planning, mainly divided into national planning, regional planning (especially in the Greater Copenhagen area) and local planning.

In Denmark, local governments are the main planners for sustainable municipal schemes, and they are responsible for the overall development of individual buildings in urban areas or energy-efficient buildings within designated areas.

The Aarhus School of Architecture, Denmark, and China’s Tsinghua University have jointly launched a joint teaching of green and sustainable buildings. China has been tracking and learning the advanced concepts, technologies and experiences of building energy conservation in developed countries.

Denmark is one of the earliest countries in the world to carry out building energy conservation and urban heating energy conservation and achieve remarkable achievements. Heating metering and other aspects have played a positive role.

China is willing to continue to actively carry out international scientific and technological cooperation with developed countries such as Denmark, further improve the technological level of building energy efficiency and low-carbon eco-city, and make greater contributions to addressing climate change!