Optimizing energy consumption in the building

The limitation of energy resources and the increasing consumption of it on the one hand and the excessive consumption of energy by different societies on the other hand, in addition to environmental pollution and wasting national funds, have put the future life of humans at risk.
Experience shows that economic growth and industrial development of countries as preconditions for political authority, national independence and cultural prosperity require various factors including energy and optimal use of energy resources. Although Iran has the richest energy resources, their improper use causes irreparable damage to the country’s annual budget. Therefore, the rational use of energy resources and planning in the fields of optimizing energy consumption have a special priority.
On the other hand, the environmental conditions of humans have a great impact on all aspects of their lives, and considering that most of our lives are spent inside buildings, creating favorable environmental conditions inside buildings is of particular importance. One of the most important conditions of buildings is the provision of proper heating and cooling and air conditioning according to the type of human activity. It is clear that the more favorable and complete these conditions are, the more money and energy they will consume. The purpose of this study and research is:
1- Proposing general changes in the design of buildings, taking into account the climatic conditions of the region.
2- The use of high-quality building materials, taking into account the issues of insulation and sealing.
3- Providing solutions to optimize energy consumption in the mechanical and electronic facilities of the building.
4- Implementing the culture of using energy consumption for users.

It is stated in history that the first uses of human energy were for heating and self-protection, and later for cooking and transportation. Undoubtedly, in the early stages of his evolution, man has also thought of building a shelter. Nowadays, the performance of buildings indirectly includes about 1.2 of the energy consumption used by different countries. More than half of the energy used in buildings is used for heating and cooling, and 10% of it is used for lighting and the rest is used for other energy uses. The energy consumption of buildings is influenced by various factors, which include:
• Local weather
• Location and orientation of the building
• Type of building design
• Type of use and how to use the building
In addition, energy management in buildings can be considered by considering the following factors:
• The location of the building
• Building cover
• Different installation systems
The choice of the location of the building determines the weather conditions in which the building is located. Building cover determines the effect of local conditions on building residents. This cover is actually a porous shell that exchanges energy, light, gases and water vapor between its two sides, the building and the surrounding environment. Installation systems complement the power of cooling, heating and light that can be obtained from the surrounding natural environment. As far as the use of these additional systems are related to the capabilities of the building cover and its local characteristics, energy consumption can be minimized. If a building is designed without considering environmental factors, that is, the building cover and mechanical and electronic facilities are designed independently and without connection with other factors, it is expected that the energy consumption in the building will reach its maximum value.
General principles of optimizing energy consumption in the architecture of a building:
1. Local weather conditions should be used in the architectural design of the building.
2. The direction of the building should be chosen in such a way that it has the best conditions for the sun and wind.
3. Trees and their shade and natural effects should be used.
4. Use plants and flowers to improve the local climate.
5. Shades should be used to reduce the heat absorption of the sun in summer and to deal with energy losses.
6. The dimensions, surface and volume of the building should be optimized to reduce energy consumption.
7. The building cover should be strengthened and insulated to reduce energy losses and air penetration.
8. The design of windows is implemented as double or multi-paned glass to reduce thermal energy losses.
9. Sealing of windows should be optimized so that air penetration is reduced and air losses are also optimized.
10. The ability to store thermal energy in the building should be provided.
11. Solar cells should be used as building components.
12. The entrances should be designed correctly and the patio concept should be used as much as possible.
13. Before designing the building, consult and coordinate with the designers of the mechanical and electronic facilities of the building.
According to the principles of optimization, it is possible to provide designs with high efficiency for buildings. Fortunately, the technology available in the country made it possible to improve the new designs of buildings and the savings made by each of these methods are significant.

However, the initial cost of some optimal buildings may be slightly higher, but the resulting savings, which often reach 50%, quickly return the additional initial investment. In certain cases, it is possible that an optimal building is cheaper than a normal building, and the reason for that is the smaller mechanical and electronic systems and low energy consumption in them.

General principles of optimizing energy consumption in building heating and cooling:
Human comfort in the building depends on four factors: air temperature, air flow speed, relative air humidity and control, soil and smell. If you pay attention to the graph of air characteristics, the comfort zone shows the range of air temperature in different seasons between 20 and 27 degrees Celsius and the range of relative humidity between 20 and 70 percent. It is more appropriate to reach the minimum temperature in winter and the maximum comfortable temperature in summer. Regarding the relative humidity, it is better to bring the ambient air to about 20 to 40 percent in dry climates and to about 50 to 70 percent relative humidity in humid regions and climates. The air speed can vary between 3 and 10 meters per minute, although air purity is also essential for human health and comfort.
In applying the principles of energy consumption optimization, it is better to first apply those optimization opportunities that do not involve any cost or have a small cost, and then proceed to the opportunities with medium and high cost, and the principles of optimization in heating and cooling are From:
1– Optimizing the space of the buildings in such a way that the spaces of the survey complex and the extra spaces are removed.

2- Optimizing the controls play an essential role in mechanical installations and by optimizing the heating and cooling controls of the building, make it possible only when necessary.

3- Reducing the thermal and cooling loads of the building: reduce the thermal and cooling loads by reducing the amount of air penetration and solar thermal energy.
4- Taking advantage of efficient facility operations: the most efficient method of heating and cooling and air conditioning should be chosen according to the type of building, climate and its residents.

5- Using efficient equipment: Choose the best equipment for the system you have chosen.

6- Taking into account the idea of effectiveness: an arrangement should be adopted so that the building and the environmental conditions are coordinated and shared as much as possible with the selected mechanical facilities.

7- People should be heated or cooled, not buildings: Spaces should not be heated and ventilated, but the places where people work should be heated or cooled.

8- Heat recovery: The heat lost from the building’s equipment and chimney, steam and electricity can be recovered.

9- Providing the possibility of energy storage: with energy storage, we will be exempted from the operation of the equipment during peak hours, and in the case of solar energy that is collected and stored during the day, it will be used during the night and non-sunny hours.
Based on the points of view presented in the general principles of optimizing energy consumption in heating and cooling, some concepts of heating and cooling emerge, and in order to optimize them, the main points of saving energy consumption are recalled with an introduction.

This section is a good guide for engineers and technicians who design, install and maintain heating and cooling systems for residential, commercial and industrial buildings. Correct understanding and compliance with the contents of this article will save the current costs of all mechanical systems of buildings. In the recent years, heating of buildings was done using oil and gas heaters, which gradually these devices have been changing and progressing and developing in such a way that today they have become smaller and more efficient than the old models, and their newer types have become automatic. . One of the advantages of new systems is the reduction of investment costs, ease of installation, low current costs and their high efficiency.
Utilization and saving in heating systems

The basic equations governing heat transfer from the walls, roof and windows of the building are:
where in :
Q : Current heat in watts
U :The overall heat transfer coefficient inw/m2 .° C
A : The heat transfer level is calculated m2
ΔT : The difference in temperature inside and outside C °
The value of U for composite walls and surfaces is:
U=1/R=1/(1/Fi +Σ X/K+1/F° )
where in :
R : Thermal resistance of surfaces
Fi و °F = The transfer coefficients of the air film are inside and outside the wall.
According to the main equation, ΔT is one of the determining factors of the amount of heat transfer and it is (ΔT=ti- t) where ti is the temperature of the inner design and t is the temperature of the outside air. In order to reduce the heat load, it is suggested that ti instead of 22°C (19)°C and °t, for example, in Tehran instead of (-5)°C in the past, assume that it is equal to (-2)°C now that in A total of 6°C decreases from ΔT, which represents a 27% reduction in heat transfer.
U is another factor to determine the amount of heat transfer, which is completely dependent on the ingredients and insulation of the surfaces.
In order to make the changes of U in the walls and windows and the roof and floor of the building tangible, a 100 square meter building in three normal conditions, with proper insulation and complete insulation has been studied and the amount of savings in this case in the amount of heat transfer in the order of zero digits – It shows 48% and 60%, which is very significant.
Another case is the reduction of the number N number of air exchange times in the equation of heat transfer through exchange air in the building, which is shown by the following relationship:
Q= V° ρ °C . (ti-t° ) .N
where in :
V : Replacement air volume m3
ρ : Specific mass of air Kg/m3
C : Specific heat of air W/Kg . ° C
It is clear that changes in N will play a major role in reducing the amount of heat transfer, provided that the reduction in air exchange does not change the indoor air conditions.
Other savings in heating systems and sanitary facilities:
• Turn off the steam system (heating) when the air temperature is balanced.

• Use efficient burners in boilers and furnaces.

• Control and adjust primary and secondary combustion air in furnaces.

• Use a water softener in the engine room and descale the pipes regularly.

• Insulate the double-wall source and the open expansion source to avoid further thermal energy losses.

• Turn off the heating process equipment when not in use.

• Use the right size steam and spa pipes and control the steam feeding system.

• Always keep the steam process under control to reduce waste from the steam distribution system.

• Check the thermal controls and always use healthy and high efficiency controls.

• Ensure proper operation of heating devices and equipment with constant maintenance and care.

• Never use electric resistance for heating because the efficiency of the process of generating and distributing electrical energy is only 20% and therefore it will involve a terrible waste of energy.

• By installing ceiling fans in halls with high ceilings, prevent the loss of hot air from the upper floors and use this hot air for heating the building.

• Use solar energy to heat domestic hot water and part of the heating of the building.

• Operate the night discount using hourly thermostat and computer control systems (the reduction of the winter design temperature of the building spaces during the night and when the building is not in use is called night discount.)

• By reducing the temperature of hot water consumption – removing the hot water system in some buildings such as schools and offices, insulating hot water pipes and using hot water flow restrictors in sanitary appliances to a significant extent in Energy consumption will be saved. Although from the point of view of saving energy consumption, reducing cold water is not as important as hot water, but following the following points will save energy consumption: Reducing water consumption – using low-consumption siphons – using water flow limiters from the bathroom shower – using low-consumption and automatic toilet faucets – reusing light wastewater for flushing toilets.

Operation and saving in cooling and air conditioning systems In refrigeration facilities, the produced heat can be used: From the hot gas coming out of the compressor – from the heat rejected in the condenser – from the hot oil of the compressor

• Turn off air conditioners during non-working hours.

• Use systems with variable airflow.

• Clean the condensers of the refrigeration system regularly.

• Inspect and clean air conditioner valves and air filters in air conditioning systems to reduce air resistance.

• Control and reduce the volume of fresh air needed in air conditioning systems.

• Use air conditioners only where they are actually needed.

• Use smart controls for the places you need and at the times you need. Despite the air conditioning system in the building, use small and independent air conditioning devices for places with special conditions. The additional cost of this system will soon be compensated by reducing additional costs.

• Because the amount of air required for heating is often less than the air required for cooling. Reduce the speed of air conditioning fans in winter.

• Check the static pressure of the air inside the building. Eliminate under-atmospheric and over-pressures to avoid increasing utility operating costs.

• Study the application of Heat-Pump heat pipes in the design of heat exchangers and use their heat exchange properties.

• Use thermal wheel in heat exchangers for heat recovery. These converters are also called rotating generators and energy recovery wheels.

• Use the building’s exhaust air for energy recovery using a heat exchanger. (Warm exhaust air warms the cold and fresh air entering the building in winter and vice versa cools it in summer and some energy is saved.)

• Use a heat pump to save energy consumption: basically, a heat pump is a refrigeration system that can be changed by a special valve to change the route of hot gas output and turn the system into a heating system. Or that the wasted heat of the refrigeration system was used sparingly. If the refrigeration system has (C.O.P) between 5 and 7, it means that for every watt of heat that is consumed in the form of electrical energy, an average of 6 watts of heat is taken from the device. Is it possible to save more?

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