HVAC maintenance and energy efficient renovations

The sole responsibility for the content of this publication lies with the authors. It does not necessarily reflect the opinion of the European Union. Neither the EASME nor the European Commission are responsible for any use that may be made of the information contained therein.

• Stuffy air when entering the room.• Windows and mirrors stay steamy for a long time in moist rooms. • Ventilators are closed or blocked.• A whistling sound due to low pressure in the room when opening

the door or window. • A sheet of paper will not move when put into the exhaust

ventilator. • There is a risk with air heating that the huge amount of

ventilation causes a draught.• Silence → the ventilation is off.• The ventilation unit is noisy→ rated too low

Signs of badly-operating ventilation

Maintenance of AC unitsThe filters of the AC unit must be cleaned or replaced at least twice a year.

• Cleaning or changing the filters always made after the pollen season. The cleaning can be done by vacuuming or using an air blow pipe for example.

• The filters will be replaced with similar new ones when the dirt of the filters reduces the air flow. A reduction in air flow increases pressure loss and the energy used by the fan; it reduces the efficiency of the heat recovery and quality of the indoor air.

• The heat recovery cell or disc is removed and cleaned every 2-3 years. Dishwashing liquid can be added to the washing water.

More instructions on the maintenance of devices in the manufacturer’s manual. The power must always be switched off during maintenance.

Maintenance of the ventilators and ducts

• Lint in the valve air gap is vacuumed out yearly. Exhaust valves in rooms with high humidity need to be cleaned.

• If necessary the valve can be released and cleaned properly. The adjustment of the valve must not change otherwise the pressure ratio will change.

• The ventilation ducts must be swept at least once every ten years.

• The condition and waterproofness of the ventilation roof penetrations must be checked every year.

The follow-up on energy use

During maintenance the systems must be checked that they are operating properly. • Has the energy use been normal?• Is the temperature and air humidity normal?• Are the occupants satisfied?• Is extra ventilation needed? Windows open?

The information from energy suppliers and energy transmission companies:• The energy use of the place• Comparison with similar buildings• Warnings of increasing use of energy sent by email • The effects of renovations and changes of heat sources on the

energy use.

Energy renovation of HVAC

The sole responsibility for the content of this publication lies with the authors. It does not necessarily reflect the opinion of the European Union. Neither the EASME nor the European Commission are responsible for any use that may be made of the information contained therein.

Energy renovation of HVACThe reason for an energy efficiency renovation is usually renovation courting some other target, like: • the end of a life span, break down or expense of

maintenance of building element or system • comfort: eliminating draught or

cold radiation• improving the quality of indoor air• maintaining the value of the real estate • updating installations and machines

according to current demands

When it is time to renovate, the prospect of energy saving should also be explored.

…and vice versa. When the energy renovation of a HVAC is done, the effects of renovation on the elements and how to use them should also be explored.

For example, when heating based on burning is changed to geothermal energy heating:• natural ventilation decreases• new ways are needed

• increasing the ventilation• increasing the airing• changing how to dry clothes• drying bathroom floors

• the temperature of the boiler room drops• increase the radiator• increase the heat insulation

Changing the heating method means looking into many other things.

The choice of heating method can significantly increase the energy efficiency

• Install mechanical ventilation and heat recovery

• Make the heating system more efficient • Change the main heating method to one

based on renewable energy• Supplement the main heating method with:

• heat pumps• solar collars or solar panels• storage heaters or stoves

• Change pumps, fans, machines and appliances to more energy efficient ones.

• Add timer-switches and a consumption control to the heating and ventilation control

• Install, replace and adjust thermostatic radiator ventilators and other control devices.

• Increase or renovate the heat insulation of hot pipes, the heat circulating water-supply system and ventilation ducts.

Improving the energy efficiency of the heat distribution system

Effects of a heat distribution method on energy use• It is important that the room feels nice and warm.

• When the reasons for feeling cold are removed, the temperature can be set lower.

• Lowering the temperature by one degree, saves 5% energy.

• Radiators under windows reduce

− the cooling of air on the surface of the window

− draughts and the down flow of cold air

− the feel of cold radiation

• Floor heating increases comfort but it can be difficult to adjust (the placement of the sensors, the storing capacity of the floor and the delay of the changes in temperature).

• Heating is comfortable under the ceiling, but under tables it is often too cold.

Calculating of the costs of various heating methods

• the cost of investment

• the price and amount of

purchased energy

• a fixed-price charge

• prices in the future

• Interest rate

• maintenance and repair costs

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Electric heating

Electric heating and fireplace

Oil

Oil and fireplace

Oil and air source heat pump

Outdoor air to water heat pump and oil

Oil, air source heat pump and fireplace

Electric heating and air source heat pump

Electric heating, air source heat pump and fireplace

Exercises

• How much energy is used in your home in a year?• What is the required power of electrical devices in

your home?• What is the average energy consumption of those

devices per day/per year? • How could energy costs be reduced?

Example: 100 m2 single-family house, built in 1990 in Tampere (regulation level of 1985-2003)

Yearly consumption• Capacity 250 m3 → ventilation 125 m3 /h (0.5 times/h)• Ventilation consumes approx. 9,000kWh if it is not heat recovery. • Approx. 15,000 kWh of the energy in a year is eddied through the envelope. • Every resident uses approx.1,000 kWh a year for water heating • The four-person family consumes altogether 28,000 kWh

Examples of how to save • By using a geothermal energy pump the savings are18,000 – 21,000 kWh (without heat

recovery)• By using an air source heat pump the savings are 12,000 – 14,000 kWh• By using heat recovery 80% of ventilation can be saved – 7,200 kWh • The geothermal energy pump + heat recovery saves 21,000 – 23,000 kWh• The air source heat pump + heat recovery saves 15,000 – 17,000 kWh• In the end, adjustment and habits determine the real saving.• In calculations: the yearly efficiency GEP 3-4, AHP 2-2.5. The importance of using electricity

4,000-5,000 kWh, has not been taken account.

Remember when choosing saving methods of energy renovations:• With heat pumps and circulating water heat distribution, the radiators will not

be as efficient as floor heating. • Two-sheet radiators are more compatible than single sheet radiators with heat

pumps. • The temperature of the room is easy to reduce by the air heat source pump

when nobody is at home. (Didn’t noticed in the previous slide)• On the other hand, the temperature in the garage or in the hobby room can

quickly be turned up for temporary use.• The amount of energy that is got from the ventilation with an exhaust air heat

pump is relatively small. It is not usually efficient enough as the main heating source in renovation.

• The energy saving of mechanical ventilation and heat recovery can be minor because usually the volume of air increases and fans consume energy.

• The tightness of the structures and the adjustment of the systems affect the efficiency.

Managing the big picture?

The windows and balcony doors were replacedthe tightness of the envelope improved but

the quality of the indoor air reducedthe exhaust air ventilation was adjusted to be more

effective and the windows had to be

kept ajar.draughts the heating had to be increased

more energy was wasted with the exhaust air

as a result, the window renovation increased the energy consumptionA better option would have been to build a mechanical input and extract ventilation with heat recovery

Remember

• When repairing, the energy saving prospects always need to be clear.

• When renovating, proper execution of the insulation, air tightness and penetrations will bring about energy savings.

• The effects of each repair on the operation of other structures and systems need to be thoroughly sorted out.

• A badly designed renovation is often the reason for moisture damage in a house.

The good practices and principles required for the energy efficient building have been included in the teaching material. The writers are not responsible for their suitability to individual building projects as such. The individual building projects have to be made according to the building design of the targets in question.