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Valentin Bonev, Kalin Hristov

(1710 - user rating)


We present the conceptual project of a Passive House which fulfills today's highest energy standards, reducing the energy consumption for heating of the building by the amazing 75%.The house is a very well-insulated, air-tight structure primarily heated by a 7.5kW geothermal pump .
Solar energy, wind energy and geothermal energy are the most widely used renewable energy sources. However, solar and wind energy production is not of a constant character and depends on the current meteorological conditions. It cannot be relied upon as the single source of energy for heating buildings. Earth, on the other hand, is an infinite source of energy. 10 metres below ground and deeper than that, the temperature does not depend on the season or the meteorological conditions above ground. All this makes the systems designed to extract energy from the underground extremely suitable for the heating of buildings. This energy source can be used on its own (the so-called monovalent systems), or in combination with other energy sources as it is done in this case.
The pump shrinks the bills during the cold winter days by 66% and together with the mechanical ventilation with heat recovery provides a constant, balanced fresh air supply. The result is an impressive system that not only saves up to 75% of the space heating costs, but also provides a unique and terrific indoor air quality. Beneath the house are situated two geothermal probes providing a quiet, clean and constant heating and cooling during the whole year. These drills reach a depth of 105m.The thermal pump is a relatively expensive system which however returns the initial cost for about 5 -6 years.
The orientation of the house is another important factor which reduces the bills to minimum, because of the solar vacuum tubes on the roof.
All of the kitchen appliances are categorized with the highest energy efficiency available on the market (category ‘A’ energy rating or better).The lighting is entirely made with LED lights.
This Passive House ensures a comfortable and pleasant environment for the habitants with very low concerns for bills and taxations and fulfills the building requirements of LEED design, that consists of a suite of rating systems for the design, construction and operation of high performance green and passive homes
This project relies on 6 different planning principles, which are of a great importance. Here are some further information about the techniques used in the project:

1.Solar vacuum tubes.
The optimal tilt of the solar panels for Bulgaria is 32o and meet approximately 50 to 60% of the annual heating demand for domestic water heating.This system has a shorter pay back period and is more reliable than other renewable energy technologies such as wind turbines or photo voltaic panels.The solar tubes are connected to 300l water storage tank providing a continuous flow of hot water to the inhabitants.

2.Mechanical Ventilation with Heat Recovery.
This system reduces the heating demand by 57%.Air is extracted from the rooms (kitchen, utility room and bathrooms). Before this air is expelled to the outside it passes through the heat exchanger in the winter garden where the heat is transferred to the incoming fresh air, thereby eliminating the need to completely heat the fresh air as it enters the building.

3.Winter Garden reduces CO2 emissions by using the plants as greenhouse fertilizer.
What also needs to be considered is the fact that modernization measures in buildings are a key driver for the economy. The measures outlined show that significant CO2 reductions are possible, with the CO2 reduction generated from the case studies being over 75%. Energy efficiency improvements are in a sector in which a reduced consumption also allows for increase in the appropriate use of renewable energy sources. The solution in this case is that the stuffy air is refined by the plants in the winter garden before discharged into the atmosphere.Thus the project becomes also green and environmentally friendly.

4.Triple glazed windows
The project uses a triple glazed windows with low-emissivity coating and insulated window frames offered by the company (Corona SL 82+).The House is glazed primarily on the south elevation to help maximising the amount of sunlight available in the short days of winter.On the other hand a firm solution with overhanging balconies helps to keep the sun out in summer when it is at it's highest,thus protecting the structure from overheating in the summer.

5.Geothermal pump
A 7.5kW (2,6 kW input) thermal pump is installed in the basement ,meeting the demands of heating the house in the winter and cooling it in summer. A Logical choice for this purpose would be geothermal heat pump heating and cooling by Folanci company (Model:FWC-03)

6.Walls with a high grade of insulation
The project uses some unique techniques of insulation that are not so expensive and still are the best for the moment. The main material is an insulation called Aspen aerogel with a low thermal conductivity. The thermal conductivity is just 0.012W/m²K .The combination of this insulation and aerated concrete blocks reduces the total thickness of the walls and other constructional parts of the building .