Dimensionering av luftbehandlingssystem och energibesparingsmetoder för laboratorier - Utvärdering av luftflödens sammanlagring och effektivisering av laboratoriers skyddsventilation

Sammanfattning: This diploma work is made for the Faculty of Engineering (LTH) at Lunds University and for the HVAC consultant company Helenius ingenjörsbyrå. The objectives were to find ways of determining what size of ventilation systems that are required for biological research and ways of lowering energy consumption focused on ventilation in laboratories, without lowering the safety for workers and environment. Only newly constructed biological laboratories are covered, but the methods and results could also be useful for other kinds of laboratories and for redesign of laboratories already in operation. The main focus is on the flowrates of ventilated safety equipment and safety ventilation. Ventilated safety equipment are equipment designed to protect laboratory workers and/or processes with the help of ventilation and safety ventilation is a broader term describing ventilation that is aimed to protect workers and processes in the whole building. These objectives are connected in that some methods of lowering ventilation energy consumption in laboratories are expected to lower the required maximum capacity of the ventilation system. Two state-of-the-art laboratory research centres where investigated in this diploma work. Karolinska Institutet Science Park (KISP) and BioCentrum (BioC). The methods used to evaluate these laboratories are examples which can be applied to other laboratories. To get a grasp of the current usage of ventilated safety equipment, surveys where performed, interviews where held, logs of airflow where analysed and visits to the laboratory buildings where done. Ways of lowering energy usage where evaluated by calculating energy usage before and after a hypothetical energy saving method. Investigations showed fairly low usage of safety ventilation. Surveys showed that laboratory workers require on average about 14 l/s in extra airflow due to use of ventilated safety equipment. During a visit to KISP building Alfa, none of the 37 observed ventilated safety equipment contributed to extra safety ventilation. Exhaust flow rate charts from BioC showed that 8 out of 117 observed fume hoods and none of the observed LAF-benches contributed to extra airflows. The installed exhaust system capacity is the maximum amount of airflow which can be accomplished with the ventilation system. The factors usually known are the initial minimum installed flow rates, the initial installed exhaust capacity and what kind of research that is mainly intended for the laboratory. The initial installed flow rates are determined by adding up all airflow rates minimum and maximum values. What is unknown is what percentage of the total available extra air flow is expected to be used at one time. In this thesis maximum observed diversity factor of air flows for biological laboratories is investigated to determine the size of HVAC system1 required. The maximum observed diversity factor is defined as the percentage of additional airflow used at one time. The maximum observed diversity factor for KISP was 94 % with projected2 lowest airflow as base and 52 % when observed weekend airflow was used as base. Observed weekend airflows are defined as the mean airflow during four Sundays adjacent to the highest observed airflow. For BioC the diversity factors where 28 %, 39 % and 59 % with projected minimum airflow and 19 %, 29 % and 13 % when airflow during weekends was set as minimum airflow. The diversity factors for KISP and one from BioC are considered unreliable due to the large difference in projected minimum airflow and observed weekend airflows. How much energy that can be saved by letting the temperature vary between 19 °C and 21 °C instead of being set at a fixed temperature is dependent on how high the fixed temperature is and the efficiency of the heat recovery. For KISP the fixed temperature is 20 °C and the heat recovery is between 50 % and 65 %. If the temperature instead would be allowed to vary, the lowering of energy use per year would be between 71 000 kWh and 110 000 kWh of for heating and cooling. BioC has a fixed temperature set at 19 °C and heat recovery is between 50 % and 65 % which gives a lowering of between 25 000 kWh and 26 000 kWh per year lowering of energy use. If the temperature was allowed to vary between 15 °C and 25 °C during nights and weekends the energy use for heating and cooling would lower with between 160 000 kWh and 240 000 per year for KISP and 270 000 kWh to 390 000 per year for BioC. To calculate the energy saving potential for lowering airflows, the energy use for a one m³/s flow during a year was calculated. When calculating a lowering of airflow, the fan power consumption also has to be taken into consideration. For KISP the energy use per m³/s was calculated as being between 73 000 kWh per year and BioC as being between 48 000 kWh and 69 000 kWh per year. Additional ways of lowering energy usage in laboratories include: Lowering of air flows for equipment which is not used – Has to be evaluated on a case by case basis. Most promising for school laboratories that are not used for long periods during holidays. Feedback – Showing people in the laboratory the amount of energy consumption in the building. Preferably with information on how they can help lowering their own contribution to this consumption. Simulate more – With better software it should be possible to do more of the laboratory work in front of a computer. Education – Teaching laboratory personnel how their work affect energy consumption and methods of lowering this. Installing automatic sash closing on fume hoods – In Emma Peterssons diploma work, around half of the fume hoods stood open during nights, which in KISP would equal 3 m³/s and an energy use of 150 000 kWh to 220 000 kWh during a year.