Author: tracy woods

Energy Efficient Renovations

Retrofitting existing homes to net zero or getting them on the path to zero is as important as building new zero energy homes. This TED Talk explains why. More and more builders are showing that it is feasible to retrofit an older home to zero or close to zero. Retrofits provide the construction industry with business during economic downturns, improve the indoor health and comfort of your customers, increase the value of their homes, create jobs by employing a wide range of workers, and help reduce carbon emissions.

Cost-Effective Steps to Zero Energy Retrofits

With a few important variations, zero energy retrofits have a lot in common with building a new zero energy home. The following steps create a framework that can be applied to any retrofit.

Energy Audit

Conduct an energy audit of the existing home including a blower door test, thermal imaging with an infrared camera, and assessments of current insulation levels, window and door quality, water heater and HVAC systems, a year’s worth of utility bills, and the efficiency of existing lights and appliances.

Energy Modeling

Use energy modeling to develop a zero energy retrofit plan that includes the degree of airtightness to be achieved, the R-value of insulation to be installed, the U-value, of the windows, and the energy efficiency of the appliances, ventilation system, heating and cooling system, and lighting required. The model should also include the cost of each proposed measure, so that the most cost-effective combination can be selected.

Insulation

Add blown-in ceiling insulation, which often is an easy and inexpensive measure. Install floor insulation or basement wall insulation. Install insulation in the existing walls by blowing it into the walls, or by removing the siding and adding rigid foam insulation to the outside of the wall before re-siding.

Lighting

Replace all the light bulbs with energy-efficient CFL or LED light bulbs. LED bulbs are preferable because they are more energy efficient, last much longer and contain no mercury. Consider adding motion detectors in areas where homeowners may tend to leave lights on.

Hot Water Conservation

Install low flow showerheads and faucets to reduce hot water use. Consider replacing an inefficient water heater with a more energy efficient model, such as a heat pump water heater. If relocating the water heater, place it as close to the kitchen and bathrooms as possible.

Heating and Cooling

If you are sticking with an existing central heating system, be sure that the ducts are well sealed and insulated. If you are upgrading the heating and cooling system, consider a ductless mini-split heat pump, which is very energy efficient and easy to install as part of a retrofit.

Energy Efficient Appliances

Replace any existing energy inefficient appliances with the most energy efficient models. Consider installing a heat pump drier.

Plug Loads

Install switches that will turn off electric outlets in home offices, family rooms and TV rooms, so that homeowners can easily turn off the plug loads on electronics, which otherwise would continue to use energy, even when they are “shut off.”

Windows

Replace leaky, energy efficient windows with windows with a U-Value close to 0.2 or install low-e storm windows, internal or external, which can save up to 20% of the heat lost through the windows.

Ventilation System

Install an Energy Recovery Ventilation System or Heat Recovery Ventilation System to provide a continual supply of fresh, filtered air in the home if the Air Changes per Hour is near or below 4.0. The Panasonic Whisper Comfort Spot ERV is an inexpensive ventilation system that may be appropriate for smaller homes.

Renewable Energy

Install or lease a solar PV system that produces sufficient kWh of electricity to power the remaining energy needs of the home.

This article was previously posted at https://zeroenergyproject.org/renovate/zero-energy-retrofits-builders/

home energy audit

Home Energy Audits

Professional energy assessments generally go into great detail to assess your home’s energy use. The energy auditor will do a room-by-room examination of the residence, as well as a thorough examination of past utility bills. Many professional energy assessments will include a blower door test. Most will also include a thermographic scan. There’s also another type of test — the PFT air infiltration measurement technique — but it is rarely offered. Check out the Energy Saver 101 home energy audit infographic to get an idea of what energy auditors look for and the special tools they use to determine where a home is wasting energy.

Preparing for an Energy Assessment

Before the energy auditor visits your house, make a list of any existing problems such as condensation and uncomfortable or drafty rooms. Have copies or a summary of the home’s yearly energy bills. (Your utility can get these for you.) Auditors use this information to establish what to look for during the audit. The auditor first examines the outside of the home to determine the size of the house and its features (i.e., wall area, number and size of windows). The auditor then will analyze the residents’ behavior:

  • Is anyone home during working hours?
  • What is the average thermostat setting for summer and winter?
  • How many people live here?
  • Is every room in use?

Your answers may help uncover some simple ways to reduce your household’s energy consumption. Walk through your home with the auditors as they work, and ask questions. They may use equipment to detect sources of energy loss, such as blower doors, infrared cameras, furnace efficiency meters, and surface thermometers.

Finding and Selecting an Energy Auditor

There are several places where you can locate professional energy assessment or auditing services.

  • Your state or local government energy or weatherization office may help you identify a local company or organization that performs audits.
  • Your electric or gas utility may conduct residential energy assessments or recommend local auditors.
  • Your telephone directory under headings beginning with the word “Energy” may list companies that perform residential energy assessments.
  • The Residential Energy Services Network provides a directory of certified energy raters and auditors near you.

Before contracting with an energy auditing company, you should take the following steps:

  • Get several references, and contact them all. Ask if they were satisfied with the work.
  • Call the Better Business Bureau and ask about any complaints against the company.
  • Make sure the energy auditor uses a calibrated blower door.
  • Make sure they do thermographic inspections or contract another company to conduct one.

This article was previously published at https://www.energy.gov/energysaver/home-energy-audits/professional-home-energy-audits

Is Passive Solar a Good Idea?

Passive solar energy designs use the energy from the sun to heat, cool, and illuminate our buildings. Solar energy is a renewable energy resource made from sunlight and nearly all of the renewable energy sources we use today comes directly or indirectly from the sun. Solar energy is environmentally friendly, and unlike traditional fossil fuels, passive solar energy is available just about everywhere on Earth. The heat and light that comes from the sun can be used in many ways to make electricity, to provide heating and cooling for buildings, or to heat water.

Potentially the sun is our most abundant source of free energy and even if a small portion of this energy were harnessed, it could solve many of our current energy problems. One way of harnessing this immense power to reduce the heating and cooling demands of a building is through the use of Passive Solar Energy.

Passive Solar Energy is the use of solar energy by passive means to reduce the heating demand of a building. A “passive” solar house provides solar cooling and heating to keep the home comfortable without the use of any mechanical equipment such as pumps or fans.

Passive solar energy relies purely on the design, positioning and style of construction of the home (or other building) allowing it to respond to the environment with nature doing most of the work.

Then passive solar energy systems are primarily concerned with the design of buildings. Passive solar design focuses on the placement of the home or building and on windows, ventilation, and insulation to cut down on the need for electricity by using the sun.

Anyone who has sat by a sunny, south-facing window on a winter’s day has felt the effects of passive solar energy and the home or building is designed to maximize the potential of this solar energy for heating and cooling, so a good solar house design is tailored to the local climate and environment.
There are several types of passive solar energy designs for buildings and these include: direct gain, thermal storage, solar greenhouse, and convective loops. The simplest form is the direct gain design in which a large south facing (in the northern hemisphere) window, usually double glazed, is used to allow sunlight into the building. The energy in the sunlight entering directly through the windows is absorbed, converted to heat, and stored in the thermal mass of the walls and floor.

But as well as using solar energy to heat our homes and buildings, we can also use it to cool them as well. Whereas passive solar heating designs collect and store thermal energy from direct sunlight, passive solar cooling can help minimize the effects of the solar radiation through the shading of windows or creating air flows using convection ventilation.

Passive Solar Heating

Passive Solar Heating is most cost-effective way of warming buildings and the goal of any passive solar heating systems is to capture and store the sun’s heat within the buildings materials and then release the heat during periods when the sun is not shining.
While at the same time the buildings elements are absorbing the suns heat for later use, there should also be enough solar heat available for keeping the living space comfortable and warm for normal daily use.

We have all seen that when an object absorbs sunlight it gets hot and we can put this to good use by allowing sunlight to pass through a window and be absorbed by the building striking directly and indirectly the thermal mass materials in the house, such as masonry floors and walls before being converting into heat.

Houses heated by passive solar energy have energy efficient windows that face south, so they absorb as much heat as possible from the sun. Once the heat has entered the building, various techniques come into play to keep and distribute it.

While direct sunlight through south facing windows can heat up a building quickly, it is much more difficult to control without the aid of a thermal mass storage wall. The thermal mass of buildings is a common concept in passive solar design. All materials can store heat to some degree so making use of heavy mass materials in the walls, floors, and ceilings gives them a higher thermal mass or heat capacity.

For example, concrete and masonry are good heat absorbers so the floors and walls can be constructed from these materials. In the hot summer time, any excess heat will be absorbed by these thermal masses to help cool down the building. Also painting the floor and walls in darker colors will help absorb the heat better.

Once the heat is in, a well-insulated and air tight building design helps prevent heat loss and allows the solar heat to provide more of the heating needed. Then the crucial component of the passively heated building is in the window positioning and design and passive solar energy makes good use of this. While normal glazed windows let heat escape, high performance windows with insulated frames and spacers, low emission ratings and multiple glazing filled with inert gas or vacuum fills, can help reduce heat loss back through the windows by over 50 per cent in most cases.

Passive Solar Heating of a Building

Conservatories are also an effective means of bringing thermal energy into houses by means of conduction through a shared mass wall in the rear of a sunroom or by using vents that allow the air between the sunroom and living space to be exchanged by natural convection. A brick chimney between a sunroom and the living room can also act as additional thermal mass. A south-facing home having an attached conservatory can in the hot summer months, use of blinds, curtains or awnings to block the sunlight and prevent the building from overheating.

But as well as large south facing windows and high efficiency windows, modern passive solar thermal designs use buildings with high (R-20) levels of wall insulation and air-tight construction to keep the heat in, when it is cold outside and keep the interior cool when it is hot outside. With the heat contained, often a simple ceiling fan is all that is required for the heat to be distributed around the building.

Passive Solar Cooling

Passive Solar Cooling is another use of passive solar energy and the opposite to passive solar heating. Passive solar cooling is more about reducing heat build-up rather than about taking it away. Cold is nothing more than the absence of heat and most of us associate cooling and air-conditioning with self-contained electromechanical HVAC devices connected to an electric power source, but the need for air conditioning in the building during the hot summer months can be greatly reduced or even eliminated by using passive solar cooling.

Passive cooling systems have the same basic components as passive heating systems but work in a different manner. Producing cooled air by making use of solar energy may seem a bit odd at first sight because we tend to view the sun as a source of heat. However, with passive solar building designs and the use of the right materials it is possible to remove heat thereby cooling our homes and buildings as well as heating them using the power of the sun.

The obvious way of shading a building is with the use of shutters, awnings, curtains and landscaping with trees, while still admitting a significant amount of indirect light. From a passive solar viewpoint, the most effective method of shading is on the outside of the building using overhangs which block the sun during the summer months but allow sunlight to enter the building during winter.

When designing with passive solar cooling in mind, heat from solar radiation and heated air should be kept from reaching the building. Natural ventilation relies on the natural airflow and breezes through windows on opposite sides of the building to reduce the need for mechanical cooling when the building is occupied. Also, cross ventilation will help distribute the heat more evenly around the building keeping it cooler.

Passive solar cooling techniques include carefully designed overhangs and using reflective coatings on windows, exterior walls, and roofs. Another way to achieve passive solar cooling is to combine shading with natural ventilation. We can design or modify buildings to use this moving air to cool the building so that the heat of the sun creates convection currents which draw cool air into the building from outside as heat rises, and cool air sinks helping to reduce the inside temperature.

Solar energy may be excluded from the interior of a structure by building walls that have good thermal insulation or cladding. Thermal insulation in walls can keep heat out of a structure during the summer and keep heat in during the winter. Expanding foam can also be used which is pumped into the wall cavity, which then fills the gap and insulates the home.

Passive Solar Energy Conclusion

The sun is free, it only makes sense to use it so by using passive solar energy design to heat and cool your home you can be both environmentally friendly and cost effective. The term “passive” indicates that no additional mechanical equipment is used so any solar gains are brought in through windows with the minimum use of electrical pumps or fans to distribute the heat or produce an effect cooling. This results in a building that responds to the environment.

Heating and cooling with passive solar energy is not as easy as you might think. Capturing the sunlight and putting it to work is difficult because the solar energy that reaches the Earth is spread out over a large area. The sun does not deliver that much energy to any one place at any one time. The amount of solar energy an area receives depends on the time of day, the season of the year, the cloudiness of the sky and how close you are to the Earth’s equator.

But a well-designed passive solar house will have comfortable, even temperatures all year round and make good use of natural light. It will therefore require less energy to heat, cool and illuminate than a conventional house. Hence it will also create less greenhouse gas emissions helping you save money and the environment.

Passive solar energy requires buildings to be located and designed so that they interact with the environment and climate in a positive manner so a passive solar home requires careful design and siting, which will vary by local climate conditions. If you are considering passive solar design for a new home or a major remodel, consult an architect familiar with passive solar energy techniques.

To gain a better understanding of how “Passive Solar Energy” works, or to obtain more detailed information about passive solar design and architecture, then Click Here today to get your copy from Amazon of one of the top books about passive solar energy concepts and practical ideas and ways you can use to heat and cool your home just by using passive solar designs.

This article was previously published at http://www.alternative-energy-tutorials.com/energy-articles/passive-solar-energy.html

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