1、公共建筑能源效率与室内空气质量外文翻译中英文公共建筑能源效率与室内空气质量中英文2018原文Energy efficiency indoor air quality dilemma in public buildingsLiva Asere, Andra BlumbergAbstractThe energy efficiency indoor air quality dilemma is a common predicament in many buildings undergoing energy efficiency improvements. The main goal of this
2、research is to study the impact of this dilemma on national final energy consumption and greenhouse gas emission reduction. A simulation using a system dynamics model was carried out. The stock of public buildings was split into four sub-categories based on when the buildings were constructed. Natur
3、al ventilation is used in all buildings before renovation. After implementing energy efficiency measures, two scenarios are simulated: one with and one without mechanical ventilation. Buildings constructed between 1940 and 1992 exhibit the greatest increase in both floor areas with energy efficiency
4、 measures and profitability ratio. The simulation results show that if ventilation is operated according to national building standards, total energy consumption in public buildings increases by 1.3 % in 2014 and by 2 % in 2040 compared to the situation where there is no mechanical ventilation. If t
5、he implementation of the energy efficiency measures is increasing at higher rate, the difference between both alternatives is increasing more. Energy efficiency measures in public buildings reduce national energy consumption and greenhouse gas emissions. However these measures also reduce indoor air
6、 quality thereby causing losses of productivity of the building occupants.Keywords：energy efficiency， government，municipalities，public building，system dynamics modelling，energy savings，CO2emissions1. Introduction and background informationThe majority of building stock in Latvia was built during the
7、 period when energy efficiency was not a priority. For the most part, these buildings do not offer the comfort and the quality of life expected today by the people who work and live in them. Due to climate change concerns, improving the energy efficiency of these buildings is a priority of the natio
8、nal energy policy. Energy consumption of public buildings, including both municipal and state-owned buildings represents a substantial part of Latvias total energy consumption. To increase energy efficiency in public buildings, EU directive 2012/27/EU on energy efficiency 1 has set a specific goal f
9、or member countries: 3 % of the total floor area of heated and/or cooled buildings owned and occupied by central governments are to be renovated each year to meet 2014 minimum energy performance standards. The same directive requires that member states set a national energy consumption and efficienc
10、y target. Improving the energy efficiency of publicly-owned buildings is therefore critical to achieving the national energy efficiency goals. To reach these goals, substantial improvement measures have to be implemented in the existing public building stock.Current building standards provide that b
11、uilding envelopes be highly air tight. This leads to the energy efficiency/indoor air quality dilemma. In spaces with high occupant density, e.g. in schools, conference rooms, offices, etc. where CO2 and VOCs are the main indoor pollutants, air tight building envelopes are to a high degree responsib
12、le for unacceptable indoor air quality. To improve indoor air quality in buildings where adequate natural ventilation is not available, mechanical ventilation systems have to be used. Such systems increase energy consumption leading one to assume that indoor air quality and thermal comfort/worker or
13、 human productivity are not consistent with energy efficiency. Studies show that the poorer the indoor air quality, the lower the human productivity (a 15 % reduction in performance of schoolwork corresponds to about 1 year of teaching 2). Excess CO2 (more than 1000 ppm) and VOCs levels in indoor ai
14、r lead to acute health effects such as irritation of eyes and respiratory tract, headaches, dizziness, loss of coordination, nausea, visual disorders, and allergic reactions, including asthma and rhinitis. Higher levels of VOCs can have chronic adverse health effects such as damage to liver, kidney,
15、 blood system and central nervous systems (CNS). Some VOCs, e.g. formaldehyde, may even cause cancer in humans 3. A review of international scientific literature shows that this dilemma occurs widely, however, there is as yet no specific solution to the problem.Studies carried out in Latvia 4, 5 sho
16、w that the operation of ventilation systems does not produce the required indoor air quality and thermal comfort, and the operation of ventilation systems can make it difficult or impossible to achieve the planned energy efficiency goals. The measured CO2 level in these cases was between 1000 ppm an
17、d 2500 ppm. One study also included a detailed assessment of the effect of the dilemma on human productivity. Results of this study show that an improvement in indoor air quality will generate a 19 % increase in productivity. But improving the air quality using mechanical ventilation systems also re
18、quires additional energy consumption, which in turn, lowers the energy efficiency in buildings. The findings in Latvia coincides with studies in other countries, e.g. the measured CO2 in schools:In UK is 21005000 ppm;In Denmark 5001500 ppm;In Poland 10004200 ppm;In Sweden 4252800 ppm;In the Netherla
19、nds 9002100 ppm;In USA 3005000 ppm.Thus the ventilation rate is only 1 l/s/person 2 while the standards and/or norms require 4.814 l/s per person depending on the category (quality class) and type of building material used 6.The main goal of this research is to assess the impact of the energy effici
20、ency/indoor air quality dilemma for public buildings on both national energy consumption and greenhouse gas emission reduction. A simulation with system dynamics model was used.2. MethodologySystem dynamics is a mathematical modelling technique, which is used to solve complex dynamic problems in non
21、-linear systems driven by feedbacks. This method is based on the study of the structure of the system and behavior generated by this structure 7. The structure is made up of stocks where accumulation occurs and flows, changing the state of the stocks.A previously-developed system dynamics model of e
22、nergy efficiency improvements in public buildings 8 is used for this study. The structure of the model is adjusted by splitting the total stock of public building into four sub-models based on construction periods (Fig. 1). The first sub- model includes historic buildings built before 1940. Most of
23、these buildings have heritage value and a limited set of energy efficiency measures can be employed. For example, as external insulation is not acceptable, internal insulation would have to be used. Buildings in the second sub-model are those built between 1940 and 1992. These have been constructed
24、according to the building standards of the former Soviet Union. The third sub-model comprises buildings constructed between 1992 and 2014. During this period, energy efficiency standards have changed twice, each time getting more stringent. The last sub-model includes buildings built after 2014: cur
25、rent building standards require that these be low energy buildings 9.Input data for each of the sub-models are presented in Table 1. They are used as initial data for simulation. Data for heated areas are obtained from the Long-term building renovation strategy 10. Insulation costs and energy consum
26、ption were collected from the database of implemented energy efficiency projects 11. The simulation period is from 2014 to 2040.Initial values used for the main general variables are:Capacity of building companies is 35000 m2/year;Heating tariff is 58 MWh/year;Electricity tariff 140 EUR/MWh;Tariff i
27、ncreases of 2 % per year;EU funds and public funding for state-owned buildings: o from 2016 to 2019 is 97.2 million EUR, from 2018 to 2022 is 38.2 million EUR;Annual public funding for municipal buildings:0.5 million EUR in 2014,1.5 million EUR starting from 2015;Every year new buildings are built a
28、t the rate of 3 %.Profitability also influences the way the model functions: the higher the potential profitability, the higher the share of funding allocated to that building group. Funding is allocated to different building sub-models based on the profitability ratio in the following way.It is ass
29、umed that only natural ventilation with an air exchange rate of 0.7 h1 had been installed and operated before the addition or implementation of energy efficiency measures. An average air exchange rate of 4 h1 created by mechanical ventilation is used for the simulation after the implementation of en
30、ergy efficiency measures. For Latvias climate, the specific energy consumption after implementation of energy efficiency measures is 9 kWh/m2/year for heating supply air and 4 kWh/m2/year for electricity with a heat recovery efficiency of 80 % and specific fan power of 1.25 kW/(m3/s) operating for 1
31、2 hours during working days.3. Results and discussionFig. 2 shows total energy consumption in public buildings both with and without the operation of mechanical ventilation systems. In both cases total energy consumption decreases. At the beginning the difference between both alternatives is 1.3 % a
32、nd increases by time and it reaches 2 % by 2040 or CO2 emissions 7050 t/year. By 2040 in 667 thousand m2 energy efficiency measures will be carried out, and this represents only 10 % of the total floor area of those buildings built before 2014. If energy efficiency measures are implemented at higher rate, the difference in energy consumption between two alternatives increases by 2040.The difference in the growth rate of building floor area with energy efficiency measures is explained by the profitability ratio the highest ratio is for buildings built from 1940 to 1992 as they h
