Due to the steady increase in energy prices and the high cost of gas supply, a growing number of developers think about building energy-efficient homes.
We have already told our readers that is energy-efficient house, and what technologies are 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'll learn:
- What house can be considered energy-efficient, and what - no.
- Can I heat the house only energy-efficient electricity.
- How to calculate the necessary thickness of insulation.
- recouped if the construction of energy-efficient homes.
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.
Not surprisingly, many developers are wary of the construction of such buildings, considering it unjustified waste of resources.
Is it really, and most importantly - profitable
Energy Efficient (energy-passive) house - a building in which the costs associated with energy consumption by an average of 30% less than a conventional house.Energy efficiency at home until recently it was possible to determine the coefficient of seasonal thermal energy - E.
- E & lt; = 110 kWh / m2 / year - an ordinary house.
- E & lt; = 70 kWh / m2 / year - energy-efficient house.
- E & lt; = 15 kWh / m2 / year - a passive house.
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 insulation in walls, roofs and ceilings of homes, glazing area and the number of people living in the building.
in Europe to determine the energy efficiency class homes EP ratio is used, which determines the amount of electricity consumed for heating, hot water, lighting, ventilation and work of household appliances.
taken as a starting point EP = 1 and energy class D, that isstandard.Modern classification of buildings adopted in European countries is as follows:
- EP & lt; = 0,25 - Class A passive house;
- 0.26 & lt;EP & lt; = 0,50 - Class B, economical house;
- 0,51 & lt;EP & lt; = 0,75 - Class C low-energy house;
- 0,75 & lt;EP & lt; = 1 - Class D, a standard house;
- 1,01 & lt;EP & lt; = 1.25 - Class E;
- 1,26 & lt;EP & lt; = 1,50 - Class F;
- EP & gt; 1,51 - Class G, the most energy-intensive home.
In normal, warmed enough, the house with the big heat loss through the building envelope, most of the energy (70%) is spent on heating.
can say that the owners of the house heat the street.
why in European countries is no surprise thick insulation in the walls of 300-400 mm, and the outline of the building is airtight.
required level of air in the building is supported by a ventilation system and not a mythical "breathing" walls.
But before buying a cubic meter of insulation, you must understand when additional insulation and the whole complex of measures related to the construction of energy-efficient homes, economically justified.
Energy in figures
In our country, the average heating season lasts 7-8 months, and the climate is more severe than in Europe.Because of this, there is plenty of debate 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 reason that in our country the construction of such houses is very expensive, and the cost of its construction will not pay off ever.Is it really?
- I in 2012, in the Nizhny Novgorod region, has built an energy-efficient house in 165 square meters.m heated area with a specific energy consumption for heating 33 kWh per square meter.per year.When the average monthly air temperature in winter -17 ° Czatraty heating electricity totaled 62.58 kWh per day.
should focus on the technical characteristics of this house:
- thickness of the insulation in the floor - 420 mm;
- thickness of insulation in the walls - 365 mm;
- thickness of insulation in the roof - 500 mm.
Cottage built on frame technology.Heating houses - low-temperature electric heaters with total capacity of 3.5 kW.Also in the house is installed the system ventilation with heat recovery and ground heat exchanger heating the outside air.For hot water additionally installed vacuum solar collectors.
Outcome: per month for heating takes 3.2 thousand. Rub.at the clock rate of 1.7 rubles / kWh.
Also interesting experience forumchanin Alexander Fedortsova (nick Offline Skeptic ), self-built brick house in 186 square meters.m on the foundation of UWB, with a homemade storage tank 1.7 m3 and crashed into him with electric heating elements.
- The house is heated by electricity through water floor heating.For heating use night tariff - 0,97rub. / KW.At night, the coolant in the storage tank is heated to the desired temperature in the morning is disabled.The cubic capacity of the house - 560m3.
Outcome: In the winter, in December, heating at a cost of 1.5 thousand. Rubles.In January, a little less - 2 thousand. Rubles.
As the experience of our users, the construction of energy-efficient homes afford any.Moreover, it is not required to equip the house with precious engineering systems such as heat exchangers air heat pumps, solar collectors and solar panels.According to Nick forumchanin Toiss , importantly - is a warm closed loop, surpassing modern building codes three times, the absence of cold bridges, Electrical window well with insulation roof, foundation and walls.
- How to pay for the connection of gas (the price of which is constantly growing) of 0.5-1 mln., It is better to build energy-efficient house with an area of 200 sq.m.With the technology of the construction and erection of the correct approach of the house is economically justified for any architectural and design solutions.
Energy - basic principles
How and what to insulate the house - one of the main issues that arise during construction.
And you need to think about it at the design stage.According Paul Orlov (nick Offline Smart2305 ), before the economic calculation justified thickness of insulation should be defined with the following initial data, namely:
1. The area of the planned building.
2. The area and type of windows.
3. Area facades.
4. The area of the basement and ground floor surface.
5. The height of the ceiling, or the internal volume of the house.
6. Type of ventilation in the house (natural, forced).
- As a basis we take a house of 170 square meters, with a ceiling height of 3 m, an area of 30 square meters of glazing.m and an area of 400 square meters walling
main heat loss in a home occurs through:
2. Walling (roof, walls, foundations).
economically balanced when designing the house should seek to ensure that the heat loss in all three categories were similar, ie,at 33.3%.In this case, a balance is achieved between the insulation and the additional economic benefit of such insulation.
maximum heat loss occurs through windows.Therefore, in the construction of energy-efficient homes is important it correctly "tied" to the site (the large windows look south), for maximum solar insolation.This will reduce heat loss in the large glass area.
- most difficult - is to reduce heat loss through windows.The difference between modern windows is quite insignificant and varies from 70 to 100 W / m.If
window area is 30 square meters.m, and the level of heat loss - 100 W / sq.m, the heat loss through the windows will be 3000 watts.Since
reduce heat loss through the windows the most difficult, that the design of insulation walling house and ventilation systems, for balance, it is necessary to strive for the same values - 3000 watts.
Hence the common home heat loss amount 3000h3 = 9000 watts.
If you only try to reduce heat loss walling, without reducing the heat loss of windows, it will lead to unnecessary cost overruns on the heater.
Heat loss through the building envelope is the sum of the loss through the foundation, walls and roof.
- We must strive to equal the heat loss through the windows heat loss through the building envelope.
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 per hour.House area of 170 square meters.m with a ceiling height of 3 m must be 500 m3 / hour of fresh outdoor air.
is calculated by multiplying the volume of floor space at ceiling height.If
ensure the inflow into the house only cold air from the street, the heat loss will amount 16,7h500 = 8350 watts.It does not fit into the balance of energy-efficient homes.
remains two ways:
1. Reduce the airflow, but it does not meet modern standards for the required air exchange.
2. Reduce the heat loss during cold air into the house.
for heating street cold air coming into the house, used the system mandatory ventilation with heat recovery.With this device, the heat of the outgoing air is passed into the street incoming flow.This increases the efficiency of ventilation.
efficiency in energy recovery is 70-80%.To learn how to build their own low-cost and efficient heat exchanger, told in this article .
- established in the house (in the example above) the system of forced ventilation with heat recovery, heat losses will be reduced to 2500 watts.Without a system of compulsory, ventilation with heat recovery is not possible to achieve a balance of heat loss in the house.
economic feasibility additional warming
basic indicators of economic efficiency of additional warming of the house - the payback period of warming.
The experience of the user with the nickname Andrew AA , compare the costs of heating with permanent insulated and neuteplёnnogo home.So, for the purity of the experiment for the initial conditions we take the following data:
- trunk gas heating;
- heat loss through the building envelope - 300 kW / h / (m² * year);
- the life of the house - 33 years.
Andrew AA .:
- First, I calculated the annual cost of heating with permanent without additional warming.After I carried out calculations the cost of heating homes in neuteplёnnogo 120 sq.m, with its heat losses to 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 insulate properly house.
Andrew AA .:
- According to my calculations, the additional warming will reduce the heat loss of my house at about 1.6 times.Hence, when heating costs, equal to 1.1 mln. 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 100% economic benefit of additional warming of the house, it is necessary that the amount spent on additional insulation, does not exceed half of the amount saved on energy costs.That
For this example, the cost of insulation should not exceed 200 thousand. rubles.
After a year of operation at home it turned out that after additional warming heat loss is not decreased by 1.6 and 2 times, and all the work done (because the insulation was carried out in the home, and the money went only for the purchase of a heater) has paid off repeatedly.
Also interesting is the approach to the calculation of the profitability of the additional warming forumchanin with the nickname mfcn :
- Consider the following hypothetical conditions:
- in the house + 20 ° C, outside -5 ° C;
- heating season - 180 days;
- house - with single frame, costing 8,000 rubles / m3, warmed with mineral wool 1500 RUB / m3;
- installation cost - 1000 rubles / m3 insulation;
- step frame - 600 mm, thickness - 50 mm.
Based on these data, a cubic meter of insulation costs 3000 rubles.
- will consider the heat loss through the walls of the house 10x10 m with a ceiling height of 3 m. From 5 cm additional insulation are 120h0,05h3000 = 18000 rubles.Lifetime houses - 50 years.The cost of heat - 1.5 rubles / kWh.
After all the calculations discussed in detail here, mfcn concluded that the optimum thickness of insulation for the house must be less than 20 cm: a further increase in the thickness of the insulation is economically unprofitable.
- As the thickness of insulation (more than 20 cm) value of the house increases linearly, and savings from insulation greatly reduced.
As to whether such an approach?
- insulated house in any case it is necessary!The thickness of the insulation must be selected, analyzed what economic effect will increase in the thickness of insulation compared to the original design.
When selecting insulation thickness normal payback period - 10-20 years.On the main modern types of insulation can be found in this article .
Given that the cost of the main gas is growing faster than inflation, it can be assumed that in the future the price of gas will be equal to the prices of other energy sources (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.
- There is such a thing as a transition from quantity to quality.At 15 cm insulation and eliminates the need for a battery, but at 10 cm, they are still needed.At 25 cm insulation can only sit on the nightly rates, otaplivayas electricity, and if the house teploinertsionny with minimal heat loss, the savings will be even greater.
key characteristic energy at home - it's heating costs!
Is it worth spending money on additional insulation at home?Due to constantly rising prices for energy investment in the construction of energy efficient homes should be considered in the long term.
is also necessary to take into account the development of building technology and the massive introduction of highly effective types of insulation, more elaborate knots and designs of homes, alternative sources of energy and heating systems.
believes that now the cost of construction of energy efficient homes in the country by 15-20% more than a conventional building of the cottage.But, for example, in the European countries in the 90's, this difference reached 30-35%, but now it is less than 8-10%.
On the construction of energy-efficient homes described in this topic.Can be cheap electricity heating?The answer to the question - here.From the diary of calculating payback from further warming of the house it can be found here.
algorithm for calculating the optimal insulation thickness is here.Having initially at this link, and then for this, you can learn how to calculate the economic feasibility of additional insulation.
In this video, see how to build energy-efficient house.But this article's accompanying video FORUMHOUSE users can learn about what is energy-passive house.