Zero Energy house

Thermodynamics

By Kawthar Khaloufi

Omar Fassi Fihri

Supervised by: Dr.Hassan Darhmaoui

Introduction:

Most of the time, we're too absorbed in modern life to realize that it is energy that makes it all possible. Every home, business, and every government. Every major issue is underpinned and established by energy. Which is why it is the most important issue of our time. We can clearly see how important it is to every aspect of our lives and thus, as engineers we should be able to improve the consumption of energy into a more efficient way.

The building sector is the largest consumer of energy in Morocco with the share of about 36% of the overall energy consumption of the country; therefore, Zero Energy house is one of the designs that implement an energy efficiency strategy. A zero energy house refers to a house with a net energy consumption of zero over a typical year. It implies that the energy demand for heat and electrical power is reduced, and this reduced demand is met on an annual basis from renewable energy supply.

Mission statement

Our job in this project is to assist a family of five people in the design of their zero energy house in the region of Ifrane, Morocco. The house consists of two floors with 120m^2 each with a large garden. The design of this ZEH carefully combines envelope efficiency, efficient equipment, appliances and lighting, and passive and active solar features, including photovoltaics (PV), while utilizing all the natural renewable energy sources the site had to offer to reach the zero energy goal.

Mission goals

Our goals for the construction of this zero energy house consists of seven important objectives. Starting with (1)Energy efficiency &

greenhouse gases by Minimising household energy usage and maximising the use of renewable energy therefore reducing carbon dioxide and other greenhouse gas emissions from energy generation. These initiatives also provide a hedge against increasing energy costs. (2)Low embodied energy by reducing the embodied energy of the house by using products and materials which require minimal energy during processing, manufacture and transportation. (3) Water conservation our target is to Reduce water use through low flow fittings and efficient appliances. This results in energy and resource efficiency by minimising supply and waste water infrastructure requirements and reduced water storage needs. Water efficiency results in a house with a greater ability to provide for its own water needs and reduces the cost of water supply and waste water disposal (4) Health & comfort, one of our main concern is to provide a healthy environment to our customers by Ensuring a warm and dry house with good daylight and fresh air supply increasing the comfort, happiness and health of occupants. This also has the potential to reduce medical costs and days off work. (5) Waste minimization, Landfill waste can be reduced by using materials efficiently, adopting recycling and reuse practises onsite and selecting construction materials that are recycled and recyclable.(6) Low pollutant emissions, Pollutant emissions can be reduced through the use low emission products and materials, stormwater management and environmental management during construction and operation. These initiatives reduce the impact on houses and environment in Ifrane. (7) Durability, Durable materials and products can help to reduce maintenance and resource costs. It is important to assess durability based on life cycle analysis.

Design of the house:

Location Ifrane, MoroccoHouse size(floor area in m^2) 120Number of floors 2

Number of occupants 5Number of bedrooms 3Type of heating system Heat pumpMain heating fuel solar and geothermal energiesOthers

We began the design by using the integrated design which is related specifically to energy efficiency. In order to achieve significant levels of efficiency, and ultimately zero energy, it required us to make an integration across all elements of the house including site, structure, materials, systems, landscape, and occupants. It costs the family 18235.19 MAD per square meter. Concerning the solar hot water, it extract the heat in the air outside of the unit and transfer that heat to the water stored inside the heater; bringing the temperature up to 55 C -60C. These units can effectively heat water even in very cold conditions as cold as -10C. In addition, The design is very easy to install . we chose as well a PV system from Perlight Solar with a high efficiency and reliability. The cell efficiency is up to 17.63% and a 25 years performance warranty. The house was designed to be warm without the need for heating, which realises two main benefits regarding the future financial and comfort of the occupants. By eliminating heating systems and the need to operate, maintain, and replace them over the next 25 years makes passive heating a cheaper option in the long-run. And Designing a house to be warm throughout without heating eliminates the struggle from mechanical heating systems issues.

After choosing the heating and power systems of the building, we looked at the actual design of the house in order to meet the requirements and goals we stated above. We came up with three important considerations that need to be taken into account in the construction of the house for a better efficiency. These are the following : 1) Solar access, 2) Natural ventilation and shading, 3) Optimally sized performance glazed windows. The most

appropriate side for both bedrooms and the living room is the north side of the house as it will benefit them from warmer temperatures and more daylight. This design will have a positive impact on energy efficiency, low embodied energy, and occupant’s health. The majority of the glazing is on the north side of the house to optimise daylight and solar gain, with glazing on the south side to reduce heat loss. Therefore; Heat is retained in the house through both high-performance glazing and a double layer of insulation as discussed in the material phase. The house has been located and orientated on the site to make the most of the site-specific sun angles. The internal layout of rooms has also been planned around which rooms need sun in the morning (kitchen), throughout the day (living areas), and evening (bedrooms).

Shading features are one of the systems that we recommended to the family in order to reduce solar gain on summer days. Shading is important because it is directly related to reducing temperature, improve comfort, and save energy. There are typical shading features that we can use for a optimum temperature control on warm days : 1) The Overhangs, 2) Fins 3) Louvres 4) Vegetation and 5) screens. It is known that during the summer the sun is most warming and heat enters the most during the late afternoon in which the sun is positioned in the west, therefore in our house design we will be keeping the glazing into a minimum in the west side of the house to help reduce the solar gain however, the glazing will be maximized in the northern side for a higher gain in heat during the winter as the trajectory of the sun in this period of the year shows that it is most warming when it faces the house from the north. We have included both the overhangs to reduce the amount of heat coming from the sun in the northern direction and corner fins that will stop some heat to enter from the eastern and the western sides of the house for the safety and comfort of the occupants during the whole year. We are also considering sliding shades along the north elevation that can be extended, contracted, or moved as required, and vegetative shading on the eastern elevation to help reduce low level sun during the summer months; it will reduce air conditioning needs and heat loss from wind. The size and

location of the windows are also relevant to the fulfillment of the energy efficiency and health comfort goals. When it came to the selection of location of the windows, it is better to put the windows facing the west side of the house to allow more heat to enter the room. Also, we used the double glazing which minimizes the heat loss through the windows and provides a good solar gain.

Fig1.South side of the house, showing reduced Fig 2. North side of the house, showing larger area of glazing in glazing area to reduce heat loss order to maximise solar gain.

Solar acess Shading system Optimal sized performance

glazed windows

0

2

4

6

8

10

12

Energy efficiencylow embodied energywater conservationhealth and comfortwaste minimisationlow pollutant emissionsdurability

Structure of the Zero Energy House :

• The construction of a Z.E.H requires a special structure which is represented by what we call "the envelope of the house " It is a very important and crucial consideration that needs to be taken into account when building our house. It consists of the walls, the roofs, the floor, the windows and the doors, the reason why these elements are important is because they can have a huge impact on the energy performance of the house. The choice of insulated walls and high performance windows will avoid us the need to heat the house during the majority of the time during the year and therefore help us save the cost. Before studying each of the elements of the structure it is important to keep in mind some consideration that we need to know before. It is known that the building envelope separates the inside of the house from the outside, protecting inhabitants from outside harming elements. After doing some research, we found out an important result which says 1) that a building envelope that avoids heating or cooling gets us 30% towards the Zero Energy goal. This means that the heating and cooling of the house should not be done by some electrical work but rather in a natural way based on the material used in the walls as well as the windows to heat and cool the house depending on the outside temperature. However, this can be done in areas where the climate is rather stable which means not too cold and not too hot. This is not the case in Ifrane because of the fact that the climate is cold during the whole year and reaches many times very low temperature below the 0°c. Ifrane holds the record of the lowest temperature ever recorded in Africa which is -24°c and this is of concern to us because it will not allow us to take into consideration the analysis we did at first as it is mandatory for us to heat the house for the comfort and the well beg of the occupants. Second, we need to keep in mind that a building envelope can't achieve high performance through products and materials alone. Knowing that the heating will still be necessary because of the very cold climate of Ifrane this does not exclude the fact that we can use some processes that will enable us to cut the costs and thus to maximize the efficiency. One of the means that can permit us to do so is the " passive

solar design" refers to the use of the sun’s energy for the heating and cooling of living spaces. In this approach, the building itself or some element of it takes advantage of natural energy characteristics in materials and air created by exposure to the sun. Passive systems are simple, have few moving parts, and require minimal maintenance and require no mechanical systems. This is one of the most cost effective ways for the performance of a building and to be able to use the passive solar gain we should 1) Face the windows towards the north, and design their size to allow the right amount of passive solar energy into the house. 2) Place living areas like the lounge, dining, and bedrooms on the warmest side of the house which is the north and spaces less lived-in such as the kitchen and bathrooms on the south.3) Place the kitchen at an eastern corner to take advantage of morning sun

Materials

As we mentioned in our goals for this project, we are very concerned with the

health of our customers as well as the environment for this reason we chose materials

based on life-cycle analysis to minimize environmental effects. Each product we chose

for the house is based on the type and volume of raw materials used in manufacturing;. Two of the most visible examples of products that were chosen with this in mind were the low-VOC (Volatile Organic Compounds ) paints throughout the house for the health and comfort of the family as it is for pollutant emissions. We chose to use a selection of waterborne paints from Resene which provide excellent protection and durability while releasing a far lower level of VOCs per litre than solventborne paints. And the non-treated cladding that is used on that exterior and within the entrance way and garage in order to minimize toxicity on site due to the fact that it has a positive health impacts. Within the walls we've also used products that minimise toxicity. We've installed non-PVC cabling throughout the house, and for the pipework have used polypropylene pipes for water supply and polyethylene pipes for water

waste. The GreenStuf insulation is also bonded using heat instead of chemicals.

Insulation is very important to reduce the amount of heat we need to generate, and therefore save energy, along with the associated pollutants and emissions. As we know the insulation properties of a material can be expressed by its K-value, The k-value is the thermal conductivity of a material, and so obviously, for insulation process we chose materials with the lower value of K as well as Insulation that contains recycled material, it is safe to handle, and can easily be recycled at end of life. It is also important that the insulation maintains its thermal properties throughout it's life. All these Low impact thermal insulation have a good impact on energy efficiency, family health, and low pollutants emissions. During the process, we made sure we are using locally sourced products to minimize transportation emissions and embodied energy, at the same time to provide good impact on low pollutant emissions, low embodied energy, and energy efficiency.

Photovoltaic and solar water heating :

Solar energy power:

This part of the design of the Zero Energy house is perhaps the most important one since it deals

with the sources of energy and its generation; as well as how these sources will be used in order

to cover the essential needs for the house and its occupants to live in comfort and for them to be

able to use all appliances that they need and benefit from the heating. Our goal for this project as

stated before is to build an energy efficient house and for that to take place, no source of energy

should be taken from other than Renewable energy sources because otherwise this won't make of

it efficient nor will it be " zero energy ". Thus, the main power sources we chose to use among

the Renewable energy sources are the Solar and the geothermal energies. Before starting to talk

about this we need to first of all know what is the total energy consumption of the house so that it

enables us to know the percentage of each energy source.

Appliances Energy Consumption Cost per year

2 TV SETs 1.32 KWh/day 24.1

Game consol 0.09Kwh/day 3.29

Refrigerator 4.32Kwh/day 157.70

Freezer 4.8kwh/day 175.22

Microwave 0.6kwh/day 21.90

Oven 2.4kwh/day 87.61

Stove 3 kwh/day 109.51

Dishwasher 1.08kwh/day 39.42

Clothes water 0.13kwh/day 4.56

Desktop computer 0.45kwh/day 16.43

2 Laptops 0.72KWH/day 13.14

Printer 0.01kwh/day 0.29

Cordless phone 0.05/kwh/day 1.75

4 Cell phones 0.04/kwh/day 0.55

Iron 0.17Kwh/day 6.02

Vaccum cleaner 0.25Kwh/day 8.51

Hair dryer 0.25 kwh/day 9.2

Water cooker 0.26Kwh/day 9.64

Lawn mowner 0.2 9.5

Heatig system Eenergy consumption Cost per year

Space heater 7.50 Kwh/day 273.78

Air Conditioner 2 Kwh/day 73.01

Lighting Energy consumption Cost per year

Light bulbs 0.30kwh/day 10.95

29%

17%14%

13%

12%4%

11%

Typical household energy consumption breakdown Heating

Coolingwater heatingAppliancesLightingelectronicsothers

From the the tables above we find the average energy consumption of a typical house is actually

in the surroundings of 12132.6 Kwh per year. Based on all the energy analysis we have made for

the typical house we expect that we will be using around 3500 kwh/a.

Photovoltaic size and selection :

The north side of the roof will be completely covered with solar, we expect the P.V array to

generate about 1250 Kwh/year for every killowatt peak installed. Thus, to meet our expected

energy usage of 3500 Kwh/a we need to install a 2.83 Kilowatt peak. We have taken into

consideration two technological options - amorphous thin film silicon and crystalline thin film

silicon. Even though they may not be the best solution or the most efficient but the choice here

was made based on the fact that a less efficiency will enable us to cover the whole area and

install 2.8 kwp hat we need in order to achieve the 3500 kwh that we need to use. If we were to

use a higher efficiency material in the solar panels it would only enabled us to use 2 .2 kwp

The grid connection

We've also planned to install a grid-connected PV array. Rather than store energy onsite in

batteries, any energy that is not immediately used in the house is exported back to the electricity

grid. When there is insufficient energy generated by the PV array for the needs of the house,

energy is imported from the grid. This type of system is more cost effective both initially and

over time as no batteries are required for set-up or replacement. Also, by not storing batteries we

are avoiding toxic elements such as lead and acid on the property. Instead, with a grid-connected

system we effectively use the grid as our battery.

Solar Water energy ( Geothermal):

As we have shown before that in a typical house in Ifrane the energy consumption of water

heating is around 14% of the total energy demand. However, for the zero energy house since we

have used the passive solar design then takes care of a part of the heating and cooling of the

house so we would expect a rise in the percentage of the water heating in the energy use to rise to

30%.

Solar water heating technologies

There are two main types of solar hot water collector used for domestic hot water heating. We will use a collector plate which is heated by the sun energy and to minimize the loss of this generated heat we will insulate the collector.

There are three main factors influencing the efficiency of the collector:

1. How much solar energy falls on the collector plate,2. How much of the solar energy that falls on the collector plate is absorbed

and transferred to the water rather than being re-radiated.3. How much of the energy absorbed by the collector plate is lost back to the

air.

we will be using the Evacuated tubes, because they can work in cloudy conditions even when the pool temperature is higher than the outside temperature. Eight collectors, insulated and covered by protective glass, are laid out next to one another to run the full length of the roof-line. The system works by pumping water to the roof, where it is heated by solar energy captured by the collector plates. Water is then returned to the hot water cylinder on the first floor of the house.

Water Water usage has direct impacts on energy consumption within a home,

which means it’s closely linked to our Zero Energy goal. using the rainwater tank leads to cut the volumetric component of water bill in half. Rainwater is collected from the roof via downpipes that feed into the underground tank which is then used to flush toilets, wash clothes, and water the garden. We expect the tank to meet around half of our water needs over the course of a typical year. Around half of the average home’s water usage is in flushing toilets, watering gardens, and washing clothes5. We’re pouring drinking water down our toilets each time we flush them. Using rainwater for these purposes means each

installed tank reduces unnecessary water treatment. Using a rainwater tank requires a pump to control distribution, and this provides an opportunity to install an efficient product to reduce energy demand, helping us achieve our Zero Energy goal. The pump uses the minimum amount of energy required. It also has an inbuilt stop function to stop operation on low demand and then restart on demand ( Ex: CME booster pump).

1. Rainwater pump 2. Rainwater tank installation

The area of a house that consumes the most water is showers, which typically account for over a quarter of the average home’s use. To reduce that volume as much as possible we’ve installed low-flow Kiri showerheads( EX: Methven brand)  to ensure great showers with less water. We paid attention to the Water of each product when deciding what to use in the house, which allowed us to easily see how much water we could expect each product to consume. So an efficient low-flow Kiri does not only save water but it also reduces the energy required to heat water.  Because the Kiri is using 40% less water it’s also using 40% less hot water, meaning 40% less water heating. Another product that saves energy are the Tahi taps we’ve installed throughout the home. They have a twin-lever mixing mechanism that separates the control of hot and cold water, meaning hot water is only demanded when it is needed. This results in less hot water and, again, less energy used.

Water efficient products that reduce hot water heating have another benefit. Because we’re heating our water using solar hot water panels, the lower the volume of hot water required, the smaller the solar hot water system can be.

In addition to that, water metering also assist in energy conservation by allowing the family to monitor their high hot water usage

1. Low-flow kiri showerhead 2. Tahi taps

water metring rainwater0

2

4

6

8

10

12

impact of water on the goals

energy efficiency low embodied energy water conservationhealth and comfort waste minimisation low pollutant emissionsdurability

Lighting:As one of the components of the house that consumes energy, well

thought-out lighting plays an important part in helping us meet the Zero Energy goal. A house in Ifrane consumes around 12% of its electricity in lightening. Zero Energy means we need to produce as much energy as we consume, so cutting that 12% down as much as we can allows us to reduce the size of the

solar system on the roof. Therefore, the lighting design is a very important process that we took into consideration from choosing the lamps to specifying the number and location of lights needed. It's therefore important to consider lighting as part of the overall integrated design process, not just something left until last.

Choosing a lighting product can make a huge difference in power bills saving. LED lights, which stands for ‘Light Emitting Diode’  a semiconductor device that converts electricity into light. LED lights are super energy efficient, using approximately 85% less energy than incandescent bulb meaning significant savings on power bills.LED lighting contains no mercury, they do not need replacing anywhere as often. This reduces the materials needed in manufacturing replacement bulbs, and also reduces the volume of materials requiring disposal.

Payback Period:

Conclusion:

Zero Net Energy buildings are a technically feasible method of reducing Morocco's

energy demand. The combination of demand side management with renewable energy sources

Provides a technically attractive way of constructing buildings with no demand on the

Utility grid. Viable renewable energy sources consist of photovoltaic cells, solar water

Heaters, and geothermal heat pumps. On the demand side, passive solar design

techniques reduce the energy demand of buildings. The use of high efficiency lighting

and appliances also contributes to energy efficiency. The fact that we were able to complete

the design and construction of the zero energy house and taking into consideration all of the

components including the comfort of the occupants and the essentials for living without

recourse to outside energy demonstrates that zero net energy is more than just a long term

vision. It is a current reality

References:

ASHRAE. (2001). ANSI/ASHRAE/IESNA Standard 90.1-2001 Energy Standard for Buildings Except Low-Rise

Residential. Atlanta, GA: American Society of Heating, Refrigerating and Air-Conditioning Engineers.

Barley, C.D.; Deru, M.; Pless, S.; Torcellini, P. (2005). Procedure for Measuring and Reporting Commercial

Building Energy Performance. Technical Report NREL/TP-550-38601. Golden, CO: National Renewable

Energy Lab www.nrel.gov/docs/fy06osti/38601.pdf

CEC. (2005). Time Dependent Valuation (TDV) Economics Methodology. www.energy.ca.gov/title24/

2005standards/archive/rulemaking/documents/tdv/. Sacramento, CA: California Energy Commission.

EIA. (2005). Annual Energy Review 2004. www.eia.doe.gov/emeu/aer/contents.html. Washington, DC:

U.S. Department of Energy, Energy Information Administration

Mermoud, A. (1996). PVSYST Version 3.3. User's Manual. Geneva, Switzerland: University of Geneva,

University Center for the Study of Energy Problems. www.pvsyst.com/. Last accessed September 2005.