Energy efficiency in hospitals – HVAC

Energy efficiency in hospitals – HVAC

Energy efficiency in hospitals – HVAC

Energy efficiency in hospitals – HVAC following lines, we will look at a number of case studies regarding energy saving options. These are subdivided into the following areas:

– HVAC

– Compressed air

– Steam

– lighting

– Cogeneration

For each of these areas, we first give a general overview explanation, followed by some practical examples from various studies carried out in the Netherlands, Belgium and Germany. In the calculations, the following rates are used for gas and electricity:

• Gas price: € 30 / MWh

• Electricity price: 80 € / MWh

Profitability calculations are made on the basis of the energy savings achieved, without taking into account government subsidies or maintenance savings that may further reduce the payback period, as government subsidies vary widely from country to country.

The underlying formulas and calculations are not presented in this guide; only the results are given.

HVAC

Energy efficiency in hospitals - HVAC
Heating, Ventilation, and Air Conditioning (HAVC)

For controlling the climate of different buildings and applications in a hospital, there are usually various air conditioning units available, distributed over different parts of the building. Depending on the application, the air can be heated, cooled, humidified and / or filtered.

Cooling, heating and humidification are generally carried out by a heat and cold production plant.

Some typical hospital applications and their particular characteristics include:

• Polyclinic and counseling services: used only during “office hours”, with air conditioning for the comfort of residents of these areas

• Infirmary: permanently occupied, with HVAC for the comfort of its occupants.

• Laboratories, dialysis services, etc. .: CVC to control the conditions of use of drugs and the tests carried out.

• Operating room and emergency room: Continuously occupied, with HVAC to control conditions within narrow temperature and humidity limits. Ventilation and filtering systems are also used to prevent contamination.

• Administrative services: used only during “office hours”, with air conditioning for the comfort of the inhabitants of these areas.

The most important areas that need to be Operating rooms are of course conditioned in a hospital. Separate HVAC units are used in this case, which in addition must comply with the specific applicable regulations (with regard to the smoothness of the interior walls, ease of complete cleaning, etc.). </ P>

Such an HVAC unit essentially comprises the following components:

• Fresh air intake section

• Coarse filtration

• Heat recovery

• Preheating unit

• Cooling unit

• Post-heating unit

• Fan

• Moisturizing

• Fine filtration

• Extraction section

Operating room

The operating theaters themselves are generally equipped with a filtering ceiling, that is to say made up of a grille fitted with a high efficiency particulate filter (HEPA) which prevents the blowing of harmful particles into the theater. .

Ventilation works on the downward flow principle, with air being blown from the ceiling at a specified speed directly above the operating table, where there is the greatest risk of contamination, to protect open wounds, surgical instruments, etc. Operating rooms are kept at an overpressure relative to neighboring areas in order to keep out dirt and contamination.

Most hospitals have several operating theaters, in which case there is usually a central air group which creates the overpressure, supplies fresh air and performs basic air conditioning for all. In addition, there is a separate HVAC unit for each operating room (or every other unit) that provides specific conditioning for the conditions required.

The air extraction unit is equipped with:

• Coarse filter

• Heat recovery

• Fan

• Extraction section

the energy consumption in a HVAC unit, the following main applications are used:

• Heat, to heat the air

• Cold, to cool and dry the air

• Electricity, to drive the fans

• Steam, to hydrate the air

The most common energy saving measures for HVAC systems in hospitals are as follows (excluding building design considerations):

• Mounting of frequency controllers on fans

• Recover heat from the extracted air

• Optimize operating hours

• Optimize temperature and humidity

High

Case 1: Reducing the ventilation rate of a polyclinic during the night

introduction

The hospital in this case is a medium-sized institution. There are different HVAC systems in the hospital, with several subsystems for each section of the building. The different HVAC systems are controlled by a building management system, the HVAC parameters being defined according to the needs of the different departments.

Current situation

The polyclinic has its own HVAC facility which operates 24 hours a day, 7 days a week. However, the polyclinic is not open 24 hours a day, which means that the HVAC system runs unnecessarily for part of the period.

Proposal

When the polyclinic is not in use, the airflow HVAC rate can be reduced to 50%. In theory, the system could be completely disabled, but for the purposes of this calculation, a rate of 50% is assumed. It is further assumed that the HVAC system can operate at 50% for 9 hours per day, during which time humidification can also be turned off.

Estimate of savings and investments

The savings are less power consumption of ventilation fans and less gas consumption, as less air has to be heated and less steam is needed for humidification.

The HVAC parameters are currently as follows:

Ventilation air supply rate: 3,800 m3 / h

Temperature : 17 ºC

Relative humidity : 70%

Ventilation hours: 24 hrs / day

Based on the above parameters, the saving can be calculated as follows:

Reduced adjustment period: 9 hrs / day

Saving electricity consumption (fans): 10 MWhe

Degree-hours based on 17 ° C (+ 1 ° C with respect to the fan): 21,577 hK / a

Gas consumption savings (heating): 7.6 MWhth

Number of humidification hours: 1,437 h / a * g / kg

Assumed efficiently of the production of steam + transport: 90%

Gas (steam) consumption savings: 5.1 MWh / year

Water saving (for information, not included in the calculation)

Case 2: Heat recovery in an HVAC group

introduction

The hospital in this case is a medium-sized institution. In the hospital, there are different HVAC systems; most of them have heat recovery but some do not.

Current situation

Currently, there is no exhaust air heat recovery in office HVAC systems, which means energy is wasted unnecessarily. In the air ducts leading to the HVAC unit, there is sufficient space to install the heat recovery.

Proposal

A Twin-Coil heat recovery system could recover approximately 50% of the heat from the exhaust air. The Twin-Coil system was chosen because of the practical feasibility of installing it in existing air ducts.

Estimate of savings and investments

The savings are made in terms of gas consumption, as less air has to be heated as part of the forced air is heated by the heat of the exhaust air. On the other hand, the amount of electrical energy consumed is higher, because installing a Twin-Coil creates additional resistance in the air duct that the fans have to overcome.

The HVAC parameters are currently as follows:

Ventilation air supply rate: 10,500 m3 / hour

Temperature : 18 ºC

Relative humidity : 55%

Ventilation hours: 18 hrs / day

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