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What is the low energy laboratory?

Nov 15, 2018

When designing energy-efficient buildings, “passive” building standards are often required. However, some of the standards and boundary conditions do not play their due role in laboratory building design.

Is it economical to build a laboratory according to passive low energy standards? This article gives detailed answers.

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Figure 1. Energy consumption needs to be optimized in the lab building as well.

The special requirements of laboratory work tend to make passive low-energy building standards difficult to implement, while also increasing construction costs. The insulation standards of passive building construction can even have the opposite effect.

Comparing passive building construction with laboratory building construction, we clearly found that implementing passive building standards does not necessarily lead to high energy-saving effects, but can achieve energy-saving characteristic values without taking other measures. In other words: the feasibility of implementing passive building standards has great limitations.

Science time is up!

The concept of passive building construction usually refers to the use of special efficient insulation measures to create a comfortable temperature environment (shown in Figure 2) in the room only by heating or cooling the fresh air. In such buildings, there is no need for active heating of traditional building techniques to heat the interior of the building.

In order to accurately assess whether a building can meet passive building requirements, people have established requirements, specific objectives, and constraints to achieve passive building construction, and as a guide for building design work.

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The above criteria are based on the technical standards of residential buildings and describe the indoor temperate climate: 15 kWh/m2a per square metre and 120 kWh maximum disposable energy demand. /m2a. It should be noted that disposable energy is energy obtained from natural energy carriers or natural resources.

In order to use, store and transport such a disposable energy source, it must first be converted into a secondary energy source, for example into thermal energy. In the process of energy conversion, energy loss will inevitably occur, reducing the amount of energy actually used by consumers. The possibility of using disposable energy directly is low and not significant.

In order to be able to compare different types of disposable energy sources, such as comparing one-time energy sources with different characteristics, different types of energy carriers have a one-time energy coefficient. Using this weighting factor, you can get the best energy demand, which is the maximum 120kW/(m2a) in the active building construction standard.

Compared to residential buildings, laboratory buildings have high indoor loads and high ventilation during laboratory work. For example, the indoor load is 80W/m2, of which the laboratory equipment consumes 55W/m2, the illumination is 15W/m2, and the personnel is 10W/m2. In addition to ventilation and ventilation, the laboratory ventilation is usually 25m3/m2/h. According to the indoor lighting amount of 15W/m2, the total power consumed for 2,500 hours per year is 37.5 kWh/m2a. Considering the one-time energy factor of 2.6, the total amount of disposable energy required is about 97.5 kWh/m2a.

In addition, ventilation and ventilation equipment also consume a certain amount of electrical energy. The power energy consumed by ventilation and ventilation can be calculated at around 25W/m2. According to the calculation of 2500h per year, the annual energy consumption of ventilation and ventilation is about 62.5kWh/m2a; the conversion to one-time energy is 163 kWh/m2a.

In this way, the single-use energy required for lighting and ventilation alone is as high as 260.5 kWh/m2a. Assume that the demand for electric energy from other electrical equipment, laboratory equipment, and air-conditioning equipment is 38.5 kWh/m2a (approximately 100 kWh/m2a of disposable energy), and the total amount of disposable energy is 360.5 kWh/m2a. This value is already three times higher than the value specified in the passive building standard; although it is assumed that central heating has been fully adopted, no form of disposable energy is consumed.

In practice, it is generally assumed that the heating demand of a passive building is 20 kWh/m2a. This data can also be adopted in order to make comparisons and estimates closer to reality. As a result, the total energy consumption required for a hypothetical laboratory building is as high as 380.5 kWh/m2a (see Figure 3).

Due to different uses, the laboratory's minimum energy requirements are much higher than the energy requirements of passive low-energy residential standards. The passive low-energy residential standard allows for a maximum disposable energy requirement of 120 kWh/m2a, which only meets the needs of laboratory lighting and ventilation, and all laboratory equipment in the laboratory cannot be used.

Table 1. Comparison of traditional building methods and passive low-energy building methods

"Passive" insulation regulations have almost no advantages

The peripheral structure of the building also has a strong influence on the heating and cooling effects of the laboratory building. A number of specific architectural design thermal simulations clearly point out that the use of passive building standards in laboratory buildings has a certain degree of significance, but it has no economic significance in the construction process.

By implementing the EnEV 2009 standard, building a laboratory with passive low-energy buildings can reduce the overall heating demand of buildings by 25%, the required heating power demand by 10%, and air-conditioning cooling by 1%. If the use of efficient heat recovery and reuse of WRG can even reduce the overall heating demand by 43%. The required heating power demand is reduced by 28% and air conditioning cooling is reduced by 2%. The capital expenditure required to achieve these savings is not proportional to the relatively improved energy efficiency.

Therefore, the current passive low-energy residential building standards do not apply to laboratory buildings with higher energy requirements. Higher payouts from laboratory building planning and investment, especially from the perspective of the typical life of a laboratory building, are not economical.

In order to be able to build truly energy-efficient laboratories, it is necessary to consider the characteristics of the building, especially the characteristics of its use: characteristics that cannot be achieved through standardization. It still needs to be as it is before: to coordinate all project-related needs and possibilities, and to coordinate energy efficiency, cost-effectiveness, functionality and comfort.