Is it profitable to build energy-efficient house

Due to the steady rise in energy prices and the high cost of gas supply, a growing number of developers think about the construction of energy efficient homes.

We already told readers of our site that that is energy-efficient houseAnd what technologies are being used in its construction.

It is time to understand how to calculate the economic feasibility of the construction of the house.

And help us in this users FORUMHOUSE.

From our material you will learn:

• What kind of house energy efficient, and what - no.
• Is it possible to heat the house only energy-efficient electricity.
• How to calculate the necessary thickness of insulation.
• Is energy-efficient home construction will pay off.

What is energy efficiency

Energy-efficient houses are built in European countries for a long time, but for our country such housing is still exotic.

Many developers are wary of the construction of such buildings, considering it unjustified waste of money.

We understand whether this is so and whether to build energy-efficient house is advantageous with regard to the climatic conditions of most Russian regions, including Moscow misrepresented.

Energy efficient (energy-passive) house - a structure in which the costs associated with energy consumption by an average of 30% less than in a normal house. recently Efficiency can be determined from the coefficient of heat seasonal - E.

• E <= 110 kWh / m2 / year - this is an ordinary house.
• E <= 70 kWh / m2 / year - energy efficient.
• E <= 15 kWh / m2 / year - passive.

When calculating the coefficient E is taken into account: the ratio of the area of ​​all external surfaces of cubic capacity to the entire house, the thickness of the layer insulation in walls, roofs and ceilings, glazing area and the number of people living in building.

In Europe for determining the energy efficiency class common to use EP coefficient which determines the amount of electricity consumed for heating, hot water, lighting, ventilation and household work appliances.

As a starting point is taken EP = 1 and energy class D, i.e. standard. Modern classification of buildings adopted in European countries is as follows:

• EP <= 0.25 - Class A passive house;
• 0.26
• 0.51
• 0.75
• 1.01
• 1,26
• EP> 1.51 - Class G, the most energy-intensive.

In the conventional insufficiently insulated housing with large heat loss through the building envelope, a large part of the energy (70%) is spent on heating.

We can say that the owners of such dwellings heat the street.

Therefore, in the European countries is no surprise the thickness of insulation in the walls of 300-400 mm, and the contour of the building is airtight.

Required level of ventilation in the house is supported by a ventilation system and not a mythical "breathing" of the walls.

But before buying a cubic meter of insulation, you must understand when additional insulation and the whole range of measures associated with the construction of energy-efficient homes, economically justified.

Energy efficiency in figures

In our country, the heating period lasts on average 7-8 months, and the climate is more severe than in Europe. Because of this, there is a lot of disputes about whether it is advantageous to build energy-efficient house with us. One of the most common claims of opponents of energy-efficient construction is the argument that the our country, the construction of such a building is very expensive, and the cost of its construction will not pay off never.
But here's a comment member of our portal.

STASNN (User FORUMHOUSE):

 I in 2012, in the Nizhny Novgorod region, built an energy-efficient house in 165 square meters. m heated area with a specific energy consumption for heating 33 kWh per square. m per year. When the average air temperature of -17 ° C in winter heating costs electricity amounted 62.58 kWh per day.

Should focus on the technical characteristics of this house:

• the thickness of the insulation in the floor - 420 mm;
• the thickness of insulation in the walls - 365 mm;
• the thickness of insulation in the roof - 500 mm.

Cottage built on frame technology. home heating system - low-temperature electric heaters with total capacity of 3.5 kW. Also in the house mounted system ventilation with heat recovery and ground heat exchangers heating outside air. To supply the hot water is further installed vacuum solar collectors.

Total score: monthly heating takes 3.2 thousand. rub. at clock rate of 1.7 rubles / kWh.

Also interesting experience forumchanin Alexander Fedortsova (forum name Skeptic), Self-built frame house of 186 square meters. m on the foundation "Swedish insulated plate", with a homemade accumulator tank 1.7 m3 and embedded therein electrical heating elements.

Skeptic (User FORUMHOUSE):

 The house is heated by electricity through water floor heating. For heating use night tariff -. 0,97rub / kW. At night the heating medium in the storage tank is heated to the desired temperature in the morning is disabled. The cubic capacity of the house - 560m3.

Bottom line: In winter, December, heating at a cost of 1.5 thousand. rubles. In January, a little less - 2 thousand. rubles.

As the experience of the users of our site, the construction of energy-efficient homes afford any. Moreover, it is not required to equip its expensive engineering systems such as air heat exchangers, heat pumps, solar collectors or solar panels. According to forumchanin with the nickname Toiss, the main thing - it's warm closed loop, surpassing modern building codes three times, the absence of cold bridges, Electrical window well with insulation roof, foundation and walls.

Toiss (User FORUMHOUSE):

How to pay for the connection of gas (the price of which is constantly growing) 0.5-1 mln., It is better to build energy-efficient house with an area of ​​200 sq.m. Subject to the construction technology and the right approach, its construction cost is justified for any architectural and design solutions.

Energy efficiency - the basic principles

How and what to insulate the house - one of the main issues that arise during construction.
And think about this need at the design stage. According to Pavel Orlov (forum name Smart2305), Before the economic calculation justified insulation thickness should be defined with the following initial data, namely:

•  The area of ​​the planned house.
•  Area and type of windows.
•  Area facades.
•  The area of ​​the basement and ground floor surfaces.
•  ceiling height, or the internal volume of the house.
•  Ventilation type (natural, compulsory).

Smart2305 (User FORUMHOUSE):

The basis take house 170 square meters, with a ceiling height of 3 m, glass area of ​​30 sq. m and an area of ​​400 square meters walling

The main heat loss in a home occurs through:

• Window.
• Walling (roof, walls, foundations).
• Ventilation.

In the design of cost-balanced home should strive to ensure that the heat loss in all three categories were about the same, ie, 33.3%. In this case, a balance is achieved between the additional warming and the economic benefits of such insulation.

The maximum heat loss occurs through windows. Therefore, in the construction of energy-efficient home is important to his right to "tie" to the area (large windows look south), for maximum solar insolation. This will reduce heat loss at a large glass area.

Smart2305 (User FORUMHOUSE):

The most difficult thing - is to reduce heat loss through windows. The difference between the modern double-glazed windows is quite insignificant and ranges from 70 to 100 W / m². If the window area is 30 square meters. m, and the heat level of - 100 W / sq. m, the heat loss through the windows will be 3000 watts.

Because reduce heat loss through the windows of the most difficult, is the design of the thermal insulation envelope home designs and ventilation system for the balance, you need to seek the same values ​​- 3000 Tues.

Hence the common home heat loss amount 3000h3 = 9000 watts.

If we try to reduce the heat loss only walling, without reducing the heat loss of windows, it will lead to unnecessary cost overruns on the heater.

Heat loss through the building envelope are equal to the sum of the losses through the foundation, walls and roof.

Smart2305 (User FORUMHOUSE):

It is necessary to strive to equal the heat loss through the windows from the heat loss through the building envelope.

It is also necessary to reduce the heat loss associated with the ventilation of premises. By modern standards, it is necessary that the entire volume of air in the living room was replaced by 1 every hour. Home area of ​​170 sq. m with a ceiling height of 3 m is necessary to 500 m3 / h of fresh outdoor air.

Volume is calculated by multiplying the floor space at the height of the ceilings.

If only ensure a flow of cold air in the house from the street, the heat loss will be 16,7h500 = 8350 watts. It does not fit into an energy-efficient home balance.

Remains two ways:

• Reduce air exchange, but it does not meet current standards for necessary air exchange.
• Reduce heat loss during cold air into the house.

To heat the street Cold air entering the house, enforced system of ventilation with heat recovery. With this device, heat of the outgoing air is passed outside the incoming flow. Thus the ventilation efficiency is increased.

Efficiency in energy recovery is 70-80%. To learn how to build their own low-cost and efficient heat exchanger, it is told in this article

Smart2305 (User FORUMHOUSE):

By setting the house (from the example above) the system of forced ventilation with heat recovery, will be able to reduce the heat loss of up to 2500 watts. Without forced system ventilation with heat recovery is not possible to achieve a balance of heat loss in the house.

The economic feasibility of additional warming

Key indicators of economic efficiency of additional warming of the house - the payback period of the thermal insulation system.

An interesting experience of the user with the nickname Andrew AA, compared the cost of heating in permanent mode and warmed neuteplonnogo home. For the purity of the experiment for the initial conditions we take the following data:

• trunk heating gas;
• heat loss through the building envelope - 300 kW / h / (m² * year);
• the life of the house - '33

Andrew A. (User FORUMHOUSE):

To begin, I calculated the annual cost of heating in permanent operation without additional warming. After I carried out calculations the cost of heating homes in neuteplonnogo 120 sq.m, when heat loss in the 300 kW / h / (m² * year), amounted to 32 thousand rubles. per year (assuming that the price for 1 m3 of gas by 2030 will amount to 7.5 rubles).

Now calculate how much money you can save if you how to warm the house.

Andrew A. (User FORUMHOUSE):

According to my calculations, the additional insulation will reduce the heat loss of my property is about 1.6 times. Hence, when heating costs, equal to 1.1 million. rubles in 33 years (32 TR per year x 33 years), after warming you can save on energy costs 1,1-1,1 / 1,6 = 400tys. rub.

To get the 100% economic effect of additional insulation, it is necessary that the sum, spent on additional insulation, does not exceed half the amount saved on the cost of the energy.

Those. For this example, the cost of insulation should not exceed 200 thousand. rubles.

After a year of operation it became clear that after additional warming of the heat loss dropped not in 1.6 and 2 times, and the whole the work done (because the insulation was carried out in the home, and the money went only for the purchase of a heater) repeatedly It has paid off.

Consider the following hypothetical conditions:

• in the building + 20 ° C, outside -5 ° C;
• heating season - 180 days;
• house - with single frame, cost 8,000 rubles / m3, warmed with mineral wool on 1500 rub / m3;
• installation costs - 1000 rubles / m3 insulation;
• skeleton step - 600 mm, thickness - 50 mm.

Based on these data, a cubic meter of insulation costs 3000 rubles.

Mfcn (FORUMHOUSE Moderator):

Will consider the heat loss through the walls of 10x10 m house with a ceiling height of 3 m. From 5 cm additional insulation are 120h0,05h3000 = 18,000 rubles. Service life - 50 years. the cost of heat - 1.5 rubles / kWh.

After all the calculationsmfcn I concluded that the optimum thickness of insulation for the building to be not more than 20 cm: further increase in insulation thickness is economically unprofitable.

See whether this approach is justified.

Smart2305 (User FORUMHOUSE):

Insulate walls is necessary! The thickness of the insulation should be selected, analyzed what economic effect will increase the insulation thickness compared to the original design.

When choosing the insulation thickness of a normal payback period - 10-20 years. Read about the main types modern heaters.

Given that the cost of the main gas is growing faster than inflation, it can be assumed that gas prices in the future will be equal with other energy prices (which are also growing). Therefore, when calculating the payback period of warming to take today's gas prices in the long term, that in the future they will remain at the same level, in 10-20 years, is wrong.

PipilatsMotors (User FORUMHOUSE):

There is such a thing as a transition from quantity to quality. At 15 cm insulation and more there is no need for batteries, but at 10 cm, they are still needed. At 25 cm insulation can only sit on the night tariff, otaplivayas electricity, and if teploinertsionny cottage with minimal heat loss, the savings will be even greater.

A key characteristic of energy efficiency - is heating costs!

Summarizing

Now it is clear whether or not to spend money on additional insulation of the building. Due to the ever-increasing prices for energy investment in the construction of energy-efficient housing to be considered in the long term.

It is also necessary to take into account the development of building technology and the massive introduction of highly species insulation, more thoughtful units and structures cottages, alternative energy sources and systems heating.

Now the cost of building energy-efficient housing in our country by 15-20% more than a conventional building of the cottage. But in European countries in the 90s, this difference reached 30-35%, but now it is less than 8-10%.

Read on about the construction FORUMHOUSE energy-efficient housing and how can the heating electricity be cheap. Meet the diary calculation Payback from further warming house and the algorithm for calculating the optimal insulation thickness. Find out, how to calculate the economic feasibility additional insulation.

IN this video See how to build energy-efficient house. Find out what energy-passive house.

Discuss the article and read other materials devoted to country life you can on the websiteFORUMHOUSE.

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