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EXAMPLES OF RENOVATION DESIGNS PRODUCED IN THE PROJECT CERtuS

MUNICIPAL OFFICES – ALIMOS GREECE

BUILDING CURRENT CONDITION – TECHNICAL AND OTHER PROBLEMS DETECTED

greece-municipal-offices

This is a detached building with a construction system typical for the period and region.The walls are insulated with 5 cm of extruded polystyrene placed in between the two brick layers. The roof slab is insulated with 6 cm extruded polystyrene while there is a mineral fibre suspended ceiling in the office space. The windows have double glazing in an aluminium frame.The envelope has thermal bridges resulting from the type of wall construction.Regarding HVAC, split air conditioning systems are used for both heating and cooling.The lighting system is mainly constituted by fluorescent T8 lamps with magnetic ballast.

ECONOMIC, FINANCIAL AND LEGISLATIVE CONSTRAINS

BRIEF DESCRIPTION

Economic/Financial Risks
As the building operates during the daytime only, the energy consumption is low compared to buildings with 24h operation. This fact affects the final payback period of the investment which is quite long, reaching 23 years for certain interventions such as thermal insulation and replacement of windows.The cost of more innovative systems (solar cooling, geothermal, etc.) is considerably high and so their integration in the building is not a feasible solution unless they are eligible for subsidies by state or other sources.
Legislative Obstacles
There is a restriction regarding the total power of the PVs which can be installed in buildings. For public buildings the installed capacity can be 100% of the maximum capacity agreed with the Utility. This limits the size of the proposed PV system even though there is space for a larger one.
The building houses the environmental and hygiene services of the Municipality. It is one-floor building surrounded by a large open area with a parking lot and a vehicle repairing facility. The construction was completed in 1986.The neighbouring buildings are in sufficient distance so that there is no important shadowing and the building enjoys full sunshine.The building has an orthogonal shape and is elongated along the E-W axis and oriented 33° from North due East.The occupation profile is from 07:30 to 15:30 on week days. There are 20 employees and about 10 visitors per day.

RENOVATION SCHEME

Opaque Envelope:
The most suitable option is the addition of 5 cm external insulation of 0.032 W/mK.
Glazing:
The optimum choice should have low–e coating glazing and window mean U-value 1.80 W/m2K.
Natural/Night ventilation:
Air vents equipped with dampers will be installed on the north and south façade of the building so as to achieve cross ventilation on each floor.
HVAC
The new HVAC system will be a multi-zone VRV system and it includes three external and forty four internal units. In addition the Heat Recovery Ventilation System (HRV), will modulate the temperature and humidity of incoming fresh air to match indoor conditions.
Lighting
All lamps of the building will be replaced with new LED lamps. Also, daylight sensors will be installed on the luminaires located close to the windows.
RES
A PV system of 26.7 kW will be installed on the roof of the building and the annual energy production will be 20,900 kWh.
Building Energy Management System
The BMS will control, monitor and record data such as air temperatures, hours of operation and power consumption, of each VRV cassette separately. Also it will control, monitor and record the lighting energy consumption of each floor separately and the operation of each Lux sensor.
In all windows and doors will be placed an on/off touch connected with each VRV cassette operation.

GENERAL INFORMATION

Year of construction:
1986
Area/Volume:
446 m2 / 1,518 m3
Building Use :
Offices
supp_zanca LEARN MORE:
Link to D2.1 pdf
Link to D2.3 pdf
Link to Guide or Brochure
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EXAMPLES OF RENOVATION DESIGNSPRODUCED IN THE PROJECT CERtuS

MUNICIPAL OFFICES – ALIMOS GREECE

RENOVATION SCHEME EVALUATION

Three alternative renovation options were carried out without the building envelope improvement with the aim to achieve lower payback time for the renovation investment and increase the potential to attract private funding. Option A excludes only the external insulation, Option B excludes only the replacement of the glazing and Option C excludes both interventions. The most financially attractive was the Option C. As can be seen the savings are comparable between the two options but the cost and the simple payback period are varying substantially. For this reason Option C was selected for implementation.
Energy Savings
The energy consumption (for heating, cooling and lighting) before renovation is equal to 30,160 kWh/year and the energy consumption per square meter is equal to 97 kWh/m2. After renovation (Option C) the consumption is reduced to 0 kWh/year. Specifically, the energy efficiency interventions, excluding the electricity generated by the PV system, reduce the energy consumption to 25 kWh/m2 by generating savings equal to 21,278 kWh/year. These savings represent 71% of the energy consumption before renovation. The remaining demand is covered up to 100% by the PV system which produces 37,300 kWh/year. The surplus energy of 28,428 kWh/year will be used on the other uses as it is mentioned above.
CO2 Savings
The CO2 savings resulting from Option C are 57.9 tons/year.
PARAMETERS OF THE RENOVATION SCHEME- TOTAL

ALL INTERVENTIONS OPTION C
Energy Savings kWh/year 59,543 58,578
Costs € 124,396 86,266
Savings €/year 7,454 7,205
Simple Payback 16.7 12.0
CO2 Savingstons/year 58.9 57.9

ECONOMIC EVALUATION

Renovations cost
The cost of the interventions which are excluded is 25,830 € for the external insulation and 12,300 € for the windows.
Economic Savings
The total annual economic savings are equal to 7,205 €. More specific the energy expenditure savings are 4,031 but post renovation maintenance is higher than before by 970 €/year so economic saving from both energy and maintenance is 3,061 €/year. Additionally, the energy expenditures of the building reduced due to the use of the surplus energy from PVs by 4,144 €/year.

FINANCING SCHEME

Under the current challenging economic conditions, municipality of Alimos has limited financial resources for implementing the energy retrofit of the selected buildings. The most suitable financing model is to assign the project to an Energy Service Company (ESCo). The ESCo is responsible to secure the total investment cost, the implementation of the project, the maintenance during the contract period and, guarantee the energy performance of the agreed solutions. The money savings, corresponding to the energy savings, will be shared between the ESCo and the municipality of Alimos, according to the “Shared Savings” model contract.
Financial Structure of Project
The most market efficient financing source for implementing the project is market money (private equity, bank loan), followed by Subsidised Loan. The least favourable one is Grants since they have zero revolving effect; Grants’ money once used, they never come back to the market. Even so, in many nZEB renovations Grants are necessary for turning a project market attractive and marketable. The optimum financial structure should involve the provision of sufficient subsidised loans as the latter improve the attractiveness of the project and make it marketable. According to the study the optimum financial structure consists of:· Equity investment by the ESCo – 14%· Subsidized Loan – 75%· VAT Facilities – 11%The expected project payback period is approximately 13 years, while the duration of the EPC is 15 years which is not favourable but still market acceptable.
Other considerations
The EPC takes into provision that the relevant money savings are allocated to the repayment of the investment, allowing 5% annual money saving to be enjoyed by the Municipality who has zero contribution to the capital cost. Once the EPC is concluded all money savings will be enjoyed by the Municipality.
INVESTMENT FOR RENOVATION – TOTAL

INVESTMENTS
HVAC 21,550
Lighting system 4,041
Renewable energy 45,977
Night Ventilation 3,874
Control system 10,824
Total Investment 86,266

municipalofficesalimos

supp_zanca LEARN MORE:
Link to D2.5 pdf
Link to D3.6 pdf

Link to D3.7 pdf