Building Energy Efficiency: A Quiet Revolution
In the last 25 years or more, the productivity of the construction industry has been decreasing and the rate of innovation has been low. Today, this trend is being profoundly reversed. From the late 1960s to the beginning of the 21st century, this relative decline in the productivity of the construction industry was evident in some countries such as the United States. In the past 15 years, many developed countries’ governments have worked hard to solve this problem. They adopt strategies to promote innovation in the construction industry and increase their productivity.
Vibrant innovation
In these strategies, the promotion of information technology has played a key role. For example, the Building Information Model (BIM) can optimize design, construction, and maintenance and is increasingly becoming a legal requirement for all public building contracts. In recent years, in the construction industry, the understanding of innovation and the mechanism for innovation and promotion have made significant progress and provided support for the formulation of more effective public policies. At the same time, on the basis of these advancements, construction companies have moved toward greater integration and increased R&D investment with different strengths.
Although this trend has emerged late, it has begun to be known to the public, which in turn has increased the demand for innovation and improved the performance of the construction and repair industry, especially in the energy sector. France recently conducted a survey: which profession is the most innovative. Construction engineers ranked fifth and architects ranked seventh. This shows that people are increasingly aware of the innovation potential of the construction industry. This is also reflected in the increased demand for end users in the construction and maintenance industries. Thanks to the information technology, the decision-making power of users is also increasing.
In terms of user selection criteria, this trend has increased the user's need for comfort, such as in terms of vision, warmth, hearing, and air quality. In addition to traditional quality requirements, construction deadlines, and industry-wide competitive standards, these new demands are beginning to affect businesses. Some innovations that improve comfort quickly are understandable, measurable, and guaranteed, and the popularity of these innovations is accelerating as end-users' voices in the decision-making chain continue to grow. Take a rapidly evolving application technology: the ceiling industry that absorbs strong sound is growing rapidly, as many scientific studies have shown that this ceiling can significantly improve students' cognitive and academic performance, not to mention improving business. Efficiency, improve the quality of hospital monitoring.
Energy saving performance
Of course, in terms of energy-saving performance, the demand for innovation is also rising rapidly, and energy-saving results are remarkable. There have been many innovations in recent years that have led to significant improvements in energy efficiency, especially in the field of insulation.
In just 10 years, the insulation of glass wool has increased by 20% while ensuring maximum health and environmental protection. The new generation of glass wool contains various proportions of biomass feedstock. Due to some environmental constraints, mineral wool is difficult to use, and manufacturers use highly insulating materials, especially vacuum insulation panels (including core materials, vacuum protective layers and compressed), or should be able to Silicone aerogel put into use. Silicon aerogels consist of a very light amorphous silicon structure in which more than 95% of the air is stored in the nanopore.
But the way to achieve energy efficiency is not just about using the best insulation technology. The physical properties of building materials, systems and automatically controlled structures, as well as active systems, also play a role. Research is active in these areas. For example, air seals and thermal bridge breakers are mandatory in the current French thermal system (RT2012). The system promotes the use of increasingly complex coating systems or membranes. A good seal helps reduce heat loss, maximizes the effectiveness of the residential microcirculation air displacement system (VMC), controls indoor air quality, and protects the interior by eliminating condensation risks. Solutions include waterproof membranes for walls and roofs (with humidity conditioning) and internal gypsum coatings for masonry walls.
The use of larger and larger glass walls also reduces lighting requirements, while increasing visual comfort and reducing heat loss. The heat transmission rate of the latest generation of three-layer glass is four times lower than that of ordinary double-layer glass, which was only entered the market 15 years ago. The electrochromic glass developed by Sage allows users to adjust color through a simple electric control facility to maximize the absorption of solar energy and significantly reduce the need for air conditioning.
Another dynamic solution is the popularity of two-way flow ventilation systems and heaters using open sensors. Manufacturers are investigating how to apply phase change materials that help regulate indoor temperature in buildings and reduce the need for air conditioning and heating. Finally, in order to test the effectiveness of all existing systems, companies are increasing their use of presentation devices. With the support of Stanford University, Leeds Metropolitan University and the Saint-Gobain Group, the UK launched an “energy-efficient home” that demonstrates the effects of renovations in a controlled environment. This is the most successful demonstration of indoor energy-saving renovations to date. Some of these demonstration devices are open to the public.
The promotion and development of these technologies will bring significant energy savings to small energy efficient buildings that exist in most European countries. The French construction industry is no exception, and some data helps us understand this. In France, the construction industry accounts for 44% of the final energy consumption in various industries, while 70% of the energy consumption in the construction industry is used for heating. So far, residential buildings have a larger proportion in this respect. The average energy consumption of residential buildings is relatively high, about 274 degrees per square meter per year. In contrast, RT2012 requires that the energy consumption of new homes in low and medium altitudes should not exceed 50 degrees per square meter per year. This upper limit represents primary energy consumption rather than final energy consumption. The final energy consumption is the energy that the user can use. Primary energy consumption refers to the energy required to produce the final energy consumption. According to the conventional energy consumption calculation method, due to the loss in the production, processing, transportation and storage process, the final energy consumption of 1 degree is equal to 2.58 degrees of primary energy consumption for electric energy, for natural gas, heating system, wood. For other energy sources, the 1st final energy consumption is equal to 1 degree of primary energy consumption.
In terms of the poor performance of the construction industry in terms of energy efficiency, the number of single-family houses is not the only factor – the energy-saving effect of single-family houses is systematically lower than that of centralized houses. The energy intensity of housing in Paris is equivalent to the national average, with 45% of housing (2.1 million of the 5.3 million units) being the least energy-efficient (E, F and G). However, the proportion of single-family houses is only 27%, while the average of urban areas in the country is 56%. At the same time, the average size of Paris houses is also significantly lower than the national average. The main reason for the poor performance of housing energy in Paris is that the renewal rate of new buildings is significantly lower than the national average and the rate of building renovation is also low. In addition to these two factors, nearly 40% of the public buildings built in France from 1950 to 1980 were in the Greater Paris area. The most common construction methods (reinforced concrete frame structures, huge glass surfaces and single-glazed glass) during that period were extremely energy intensive.
Significant potential for energy savings
In view of the current status of European architecture and the power of technology available today, the insulation system of standard residential buildings constructed according to the French RT2012 standard, which is not high in energy intensity, can reduce the heating cost to 1/10 of the current cost. If you use the previous version of RT2012 implemented in 2005, you can also reduce it to 1/3. If the requirements of RT2005 are implemented across Europe, the achievable energy savings will be 41.868 GJ, equivalent to 500 million tons of oil, equal to the sum of primary energy consumption in France and Germany!
Is it difficult to achieve such energy savings? To assess this, we'd better consider an F-class energy-efficient house built in Nancy in the 1960s. This type of house currently accounts for 30% of French houses. With an up-to-date fuel-driven heater, the average annual heating bill for this home is €3,300. In residential areas, the most cost-effective and best-performing short-term intervention is to improve the energy efficiency of the building's outer casing, and this home is no exception. As a first step, a simple project can be implemented for top floor insulation and external insulation, double glazing, and a one-way flow VMC system, which costs about 10,000 euros, which can increase the energy efficiency of the house. Class C, halving the heating bill. Even if you don't consider the added value to the house, the investment can be returned within seven years. If other projects are implemented at the same time, such as refurbishment or planned expansion, the rate of return will be higher. With variable-rate loans, such improvements will immediately save homeowners cash.
Due to this significant saving potential and high socio-economic benefits, most developed countries have increased the energy efficiency standards for construction projects in recent years. This also explains why most European countries emphasize building insulation in energy system upgrade legislation. These legislations usually stipulate three priorities: to improve existing buildings while improving new building standards; to encourage or require insulation engineering at critical moments in the asset life cycle, such as regular roof repairs or exterior repairs; Special projects for energy efficiency projects. According to the goal set by the World Green Building Council (a coalition of builders established to promote sustainable buildings), in order to keep the global warming effect within 2 degrees Celsius, the construction industry should emit carbon dioxide by 2050. Reduced to 84 billion tons. From a global perspective, these initiatives represent an effective effort to achieve this goal.