How to calculate heat loss and make an energy-saving house plus energy class project in accordance with the criteria of a passive house.

 

We were approached by a person who liked our project of an energy-saving house called the project Regina 2 but he had a desire to make his house as energy-efficient as possible.

We undertook to calculate heat losses and find optimal solutions to minimize them.

First we do an energy audit of the project.

The purpose of calculating energy losses:

1. Determination of energy consumption for heating and cooling

2. Determination of consumption for hot water and electricity

3. Selection and comparison of different energy supply systems

4. Calculation of the optimal heat pump power

5. Determining the monthly energy balance

6. Assessment of electricity generation using a photovoltaic system on the southern slope of the roof.

Initial data in the basic version of the project:

• Two-storey house with a building spot of 132.5 m2 and a total area of ​​199 m2

• The number of permanent residents - 5 people

• Placement of the entrance to the house to the west. The most glazed facade is oriented to the southeast.

• Walls aerated concrete block with insulation 200 mm

• Foundations tape monolithic with insulation of 200 mm

• Metal-plastic Rehau Synego MD 82, double-glazed window 4zero-19ar-4-19ar-4en2 with a warm distance.

• Overlap of the second floor reinforced concrete with insulation of 350 mm expanded polystyrene

• Supply and exhaust ventilation system with heat recovery efficiency 83% /

• Possible systems for heating and hot water supply - electric boiler, gas boiler, heat pump.

• Installation of a solar system is possible.

Estimated ratio of heat loss and heat gain:

 The distribution of the costs of operating a house with electric heating. Energy Efficiency Class B +

The monthly balance of the costs of operating a home. The required power of the heating system is 8 kW. 6 kW cooling systems

Comparison of heating and cooling costs when using different systems:

Distribution of operating costs for heating, cooling and domestic hot water from a ground heat pump.

Analysis of the illumination of the rooms of the house with natural light (daylight factor, the optimal value is 3%)

Active House Score

According to this graph, we see that it is possible to improve illumination, reduce energy consumption, add energy generation. Ecological criteria of the house are determined by the design features of the project and are not amenable to improvement.

Next, we will find more effective solutions for home insulation

1) Improving the tightness of the house according to the recommendations of the passive house to 0.6 1 / hour with verification through blowerdoor tests

Depending on the quality of construction work, the cost of improving the isolation of the house from 0 to 40,000 UAH. It depends on the need for additional sealing of the assembly joints and joints.

The event is definitely recommended.

2) We check the rationality of increasing the size of the southern windows (up to a height of 2400 mm)

a) Without active sun protection, increasing window size increases air conditioning costs

b) With the use of active sun protection, the savings will be 1480 UAH / year with an increase in investments by 60,000 UAH, but the use of active sun protection makes it possible to minimize the need for conditioning. And when using a soil heat pump with a passive cooling module (use for cooling a soil circuit), completely abandon active cooling.

3) Thermal separation of the foundations of the house and the porch

Estimated investment 2160 UAH. Saving 128 UAH / year and the lack of a cold bridge. Recommended

4) Organization of thermal break between the inner walls and the foundation (insulation of the inner walls of the foundations)

Estimated investment 28,000 UAH. The savings are negligible. Not recommended.

5) Increasing the thickness of insulation EPS, Neopor 18 - 250, 300 or 350 mm instead of 200 mm

a) Eco expanded polystyrene with graphite Neopor 18 - 250 mm (1900 UAH / m3)

Additional investments approximately - 26 030 UAH

Annual savings from improving energy efficiency - from 483 UAH / year (Payback - 53 years)

b) Neopor 18 (1900 UAH / m3) - 300 mm

Additional investments approximately - 54 060 UAH

Annual savings from improving energy efficiency - from 1143 UAH / year (Payback - 64 years)

c) PSB-S 35 - 350 mm,

Additional investments approximately - 1370 UAH

Annual savings from improving energy efficiency - from 753 UAH / year (Payback - 2 years) Recommended

6) Check the increase in the thickness of the insulation of the roof from 350 to 550mm

a) Insulation 450 mm

Additional investments approximately - 25 080 UAH Annual savings from improving energy efficiency - from 1021 UAH / year (Payback - 24 years) Recommended

c) Insulation 550 mm

Additional investments approximately - 50 160 UAH

Annual savings from improving energy efficiency - from 1190 UAH / year (Payback - 42 years) Not recommended.

7) Checking the increase in the thickness of floor insulation from 200 to 250

a) Insulation 250 mm

Additional investments approximately - 15840 UAH

Annual savings from improving energy efficiency - from 227 UAH / year (Payback - 69 years)

Not recommended

8) Using Rehau Geneo PHZ windows

Additional investments - 50 000 UAH. Annual savings from improving energy efficiency - from 557 UAH / year (Payback - 89 years)

9) Installation of windows in the insulation layer (external installation)

Investments - 70 036 UAH Annual savings - from 875 UAH Payback period of investments - 79 years

10) Use of smart thermostats Nest, Tado, Netatmo or similar

11) To reduce overheating, the use of active external shading is recommended.

 

Estimated additional investment - UAH 67,000

Savings on cooling - 500 UAH / year

Passive cooling is only possible with underfloor heating.

Estimated reduction in the cost of Cooling systems from 60,000 UAH

 

 

 

 

 

 

 

 

12) Application of heat pump and solar power station

When installing a solar photovoltaic station on the southern slope of the roof, increasing the size of the southern windows and using a geothermal heat pump, we will get a level of energy production that will significantly block energy consumption.

According to the annual energy balance, we get home energy plus which produces more energy than it consumes.

When connecting the green tariff, the profit from the sale of electricity to the grid (for 2020) reaches 1844 euros.

Estimated additional investment - 572000 UAH. Savings on cooling - 500 UAH / year. It is possible to use passive cooling only using underfloor heating and ventilation systems. Estimated reduction in the cost of cooling systems from 60,000 UAH. Return on investment 21 years.

The balance of energy consumption when implementing recommendations.

Balance of heat loss and heat gain

Balance of energy consumption and power generation from a solar power station

The required thermal power of the heating system (heat pump capacity) is 4 kW, the required power of the cooling system is 2 kW.

Assessment by criteria of an active home

To improve the parameter of drinking water consumption, solutions are needed to collect rainwater and purify gray water for the needs of the garden, toilet and so on. To improve environmental parameters, certified and recycled materials should be used, as well as other structural solutions to reduce the logistic component in the carbon footprint.

With sufficient insulation, this house can be made passive to receive the Passive House label.

Excerpt from passive house planning package PHPP

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