This page contains a Flash digital edition of a book.
HVAC SYSTEMS


Humidification: 29.6%


Outside air heating: 48.0%


Roof: 9.1%


Windows: 52.5%


• Roof: RSI = 3.5 (m? x °C)/W (averaged value for the whole building).


(adjusted value due to window frame).


Envelope heating: 22.4%


Figure 2: Distribution of energy consumption for heating.


Walls: 38.4%


Figure 3: Distribution of the energy consumption for heating the envelope.


‘Heat recovery of exhausted air by an enthalpy and sensible heat recovery device (such as an enthalpy heat recovery wheel) offers a way to drastically reduce the amount of energy required for heating.’


Energy analyses of several hospitals show that the air conditioning (heating and cooling) of a large amount of outside air introduced into a health care building for ventilation purposes are a major source of energy consumption. For example, let us look at the energy usage of a multi-service short-term 75,000 m2 hospital located in Quebec City in Canada. The average climate temperature in Quebec City is relatively cold, with 5,200 degree-days of heating requirements compared to that of Toronto, which has 3,650 degree-days requirements.


Building description The Quebec City health care building is composed of six different wings with 300 beds for patient care. One quarter of the floor usage is for short-term acute care services (intensive care unit, bone morrow transplant, kidneys transplant, blood dialysis, etc). The short-term acute care units are occupied with patients on a 24/7 basis. These services are in direct relation with the emergency, medical imaging, radiotherapy, surgical operating rooms, the pharmacology unit, the sterilisation units, etc. Other general services are also included, such as a food preparation unit, a cafeteria, maintenance, several shops, and the building operation services.


The HVAC design was based on the IFHE DIGEST 2014


CSAZ317.2-10 Standard which imposes major requirements on the characteristics, operation, and redundancy of the all mechanical and electrical equipment for hospitals. One of these requirements relates to the amount of outside air required for ventilation of the different services. The thermal resistances of the several components of the envelope used are as follows: • Walls: RSI = 3.3 (m2


value for the whole building). • Windows: RSI = 0.39 (m2


2,800 2,400 2,000 1,600 1,200 800 400 0


1 465 929 1393 18 232157 27 324 37139 85 Figure 4: Hourly heating load (improved building). 37 77


x °C)/W (averaged x °C)/W


In concordance with the CSAZ317.2-10 Standard, all rooms of the hospital are cooled and heated with several air-handling systems. In general, one system is used for each service unit. The total outside air for ventilation is 131,450 l/s, with most of it supplied 24/7. The inside temperature is kept at 25˚C for cooling and at 24˚C for heating. It is mandatory to ensure excellent comfort conditions before any energy efficiency improvement measure that could have an impact on comfort. A reduction of productivity because of non-comfortable ambient conditions is much higher in cost than the savings achieved with better energy efficiency. The following simulation of the building performance does consider that the ambient temperature is kept at the most acceptable conditions. The simulation takes into account a lighting power density of 21.5 W/m2


in the


most acute services and a lighting power density of 16 W/m2


in other services. Based


on statistics compiled in several heath care buildings, the hot water usage is distributed at 60˚C and the usage is 136,200 L (average) per day.


Simulation results The simulation of the reference building gives a total energy usage of 23,800,000 kWh of electricity and 4,500,000 m2


of natural


gas. The gas consumption takes into account the standard combustion efficiency of natural gas. In kWh equivalent, the annual energy usage is 71,200,000 kWh with a unitary usage of 950 kWh per m2


of gross floor area.


For the non-efficient building, the distribution of the energy usage per service is presented in Figure 1. On this chart, the


several services identified are: Lighting: This is the interior lighting used in the building (essentially based on the


Hourly heating load


41 4641 51 55 603369 05 Hours (1 year)


64 69 74 78 8353892561 97


Heating load (kW)


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100