Cooling Without Air Conditioning

As we increasingly experience summer weather during winter months, some locals are deciding to add air conditioning to their homes. Air conditioning draws significant electrical power, most of which is generated from fossil fuels, thus exacerbating the warming that this equipment is designed to counter, at least indoors. Even when powered by renewable energy, caution is advisable, since the production of any AC equipment uses a lot of resources.

If not air conditioning, what other options make sense? Adding exterior shading devices over windows that are bathed in the sun’s heat is one possibility. These can be trellises, with or without deciduous vines; canvas awnings that are fixed, manually adjustable or even motorized; fixed eyebrow extensions; vertical louvers or fins for east and west facing windows; or mesh solar shades that slide in vertical tracks on either side of the window which can cut out as much as 80% of the heat.

These exterior shading strategies are more effective at controlling solar gain than interior shading blinds or curtains. Well-designed sun control and shading devices can dramatically reduce building peak heat gain, while also improving visual comfort by controlling glare and reducing contrast ratios.

Another option is to change the glass in south facing windows to high-performance glazing that has a very low shading coefficient (SHGC-solar heat gain coefficient). Such glazing greatly reduces the need for exterior shading elements. To carry out this change, sometimes just the glass panels in old windows can be swapped out. At other times the entire window frame and sash need to be replaced to get optimal performance. This latter approach is expensive but does have advantages beyond just keeping unwanted heat out.

Top performing windows can also attenuate outside noise and keep the place warmer on cold winter days. Putting an operable window in a key location, where perhaps none existed before, can allow residents to open a house to cool early morning air on hot days, thereby implementing an effective natural cooling strategy.

Consider adding insulation to your existing walls and attic. In most cases this is less expensive than installing air conditioning equipment and helps not just to keep the house cool but also quiet and, when desired, warm as well. It definitely saves on heating and cooling bills. There are at least five materials and approaches to insulating existing houses: loose-fill cellulose, dense-packed cellulose, loose-fill fiberglass, dense-packed fiberglass and injection foam. Application skill is important for achieving a complete, high-performance thermal barrier, so getting the help of a professional is advisable.

A final, low-cost cooling option is to install Casablanca ceiling fans in the main rooms of a house. These don’t lower temperatures but they move air, thus making us feel cooler. If a room has a central ceiling light, a combined fan-light fixture can easily replace it.

Consider exploring these options before automatically turning to air conditioning.

Specifics for a Resilient House

Structural Considerations:

Meet or exceed current seismic codes for tie downs, lateral (sheer) bracing, masonry chimney supports, etc.

A building’s ability to flex and absorb vibration is as important as how strong it is when it comes to earthquake resistant design. Install expansion joints to allow a building to move without damage during seismic activity.

Fire Resistance:

Use non-combustible materials for the building shell: 3 coat plaster, cementitious siding, clad or metal frame windows, clay or concrete roofing tiles or standing seam metal roofing. Avoid exposed wood outside. If have exposed wood, coat with water-based intumescent paint.   Avoid attic venting [use foam insulation (Icynene) to meet code]. Consider metal gutters integrated with metal facia. Use gutter guards to keep gutters cleaned out. Since eaves are one of the most vulnerable areas, cover with non-combustible material like plaster or cementitious boards.

Make deck surfaces non-combustible with tile or masonry combined with plaster skirting and plaster or metal guardrails.

Make structure super tight to prevent/minimize smoke intrusion.

Top chimneys with ¼” mesh spark arrestors.

Install state-of-the-art flame and ember resistant foundation vents. Use similar vents for soffit, ridge and gable openings, if they exist, but try to avoid. Brands to consider are Vulcan, O’Hagin, FAMCO, Ember Out and Brandguard.

Establish defensible space around your home, by planting fire resistant landscaping, keeping trees limbed up and cleaning debris around the house. Absolutely no wood or other combustible material should be stored near the outside of your house.

Protect from Extreme Weather:

Reinforce structure to withstand severe wind loads (basically same steps as for seismic strategies)

Prepare for heavy precipitation and flooding. Use deep overhangs (suggest 24”) to keep much of the rain away from the house. Use gutters, downspouts, French drains, soil slopped away from structure and site swales, infiltration basins and catch basins to let water penetrate ground and protect the building from heavy storms. (Can use gutter system to capture and store rainwater for future irrigation).

Provide permeable surfaces at patios, walkways and driveways to absorb storm water.

Build drainage planes behind wall skins to allow trapped moisture/water to escape and drain out at base of walls.

Pay special attention to basements and crawlspaces where water may collect. Locate mechanical equipment and electric panels above grade. Attic spaces are ideal for such equipment (furnaces, boilers, AC equipment, and water heaters).

If located in a flood plain or the coastal zone, think about rising seas, storm surges and even possible tsunamis. Elevate the main living quarters and install breakaway walls at the lower level. This is standard practice in Hawaii.

For Survivability:

Employ passive solar design strategies. Create a tight shell with substantial insulation, thermal breaks, thermal mass, strategically placed windows, natural ventilation, stack ventilation, and moveable shading devices on the sunny sides of the house. Maximize daylighting. These steps can save operating costs and assure a reasonable level of comfort when heating/cooling equipment is out of commission.

Go All-Electric with Backup Storage:

Use Energy Star or better appliances or equipment. Use heat-pumps for heating, cooling, hot water and clothes drying. Install a magnetic induction stove for cooking. (Emergency back up for cooking could be a Coleman camp stove using propane cannisters). Generate your electric power with photo-voltaic panels and a backup storage system (maybe Sonnen-a German battery). Arrange your electric circuitry for survivability. Run your refrigerator, cooker, some minimal LED lights, your media/information center and at least one receptacle for charging phones off the battery backup system. A Yeti Tundra 65 cooler makes an effective emergency backup for frozen foods when power goes out.

Consider an electric vehicle or bicycle (electric or pedal) in case of an extended power outage where gasoline will not be available. Avoid a diesel generator for backup. Fuel may not be available plus it contributes to the climate crisis.

Develop an Emergency Water Supply:

Stored water, perhaps collected rainwater, can be purified/filtered with an MSR Guarding Purifier System.

What Makes a Home "Green"?

Multi-year drought, distressed forests and intense wildfires bring awareness of the local impacts of climate change. Efforts to address climate change have long focused on cutting greenhouse gas (GHG) emissions and more recently on sequestering carbon. But because the impacts of climate change are now upon us, we need to add to our efforts resilience planning. What is the focus of these efforts related to our buildings?

In reviewing many “green building” programs, the most common characteristics are: energy efficiency, water conservation and selecting materials that are sustainable and used in a resource-efficient way.

Because energy use is strongly linked to GHG emissions, reducing energy consumption in homes tends to decrease damage caused by burning fossil fuels. There are many ways to reduce energy use in homes: install more efficient appliances, select higher performance windows, or add thicker insulation.

Water conservation makes sense in most regions of the country, excluding only those where fresh water is abundant. In California, water is directly linked to energy, for close to 20 percent of our energy use statewide is consumed in transporting and treating water. Residential water conservation emphasizes careful selection of plumbing fixtures and appliances but also promotes rainwater collection.

Choosing materials for a green home involves selecting materials that are naturally renewable (for example, wood from sustainably harvested forests), have recycled content, or are harvested/manufactured regionally. These materials also need to be incorporated in structures as efficiently as possible.

Other green building criteria worth considering are:

·         Designing and building homes that last longer. Although rarely thought about, designing to make future changes easier helps save materials. Selecting materials that require less cleaning and less maintenance are also aspects of durability.

·         A green home is small. Scaling down is unpopular with Americans, but greatly reduces impact.

·         A green home provides superior indoor air quality and promotes human health. Avoiding materials and furnishings that involve toxins and outgassing is key. Good natural and mechanical ventilating is also important.

·         Because transportation involves our biggest consumption of fossil fuel, selecting a location that is close to work, shopping, schools and public transportation could be the most impactful of all criteria, but is rarely addressed.

Resilience focuses on livable conditions in buildings after a disaster; on backup power; and on access to potable water. These strategies are being woven into “green building” programs but expanded to community scale. Photovoltaics with on-site storage can provide basic services and information during power outages. We know how to build tight buildings out of non-combustible materials to resist wildfires. Mechanical ventilation with HEPA (high efficiency particulate air) filters can handle smoke and ash from wildfires. Rainwater collection, composting toilets and recycled water are other resilient strategies.

Instant Hot Water with Less Waste

Hot water is typically the second largest use of energy in a home (after space heating and cooling). Despite its resource intensity, the hot water delivery system is seldom an area of focus when constructing a home. As a result, many homes have systems that take minutes to deliver hot water to the faucet and waste large amounts of energy and water in the process. Approximately 10-15 percent of energy use associated with hot water is wasted in distribution losses.

A brief article appeared in The Independent a few months back promoting hot water recirculating systems as a way to save water. A recirculating system is a hot water line that loops throughout the house connecting to all the fixtures that use hot water before returning to the water heater. These systems usually have a timer that runs a pump during fixed periods of peak hot water usage. By continuously circulating hot water during peak periods, it provides instant hot water and saves water by eliminating the water that typically runs down the drain while waiting for hot water to arrive. Water is saved but only by using an excessive amount of extra energy.

Another drawback: the pipes tend to fail prematurely (usually in 5-6 years) by corrosion from the continuous flow velocity of the water and from the water chemistry—certainly an issue in Santa Barbara with our hard water.

Another more sustainable option is on-demand hot water delivery, a system that is compatible with tank or tankless water heaters and works with solar hot water units as well -the greenest option. At the push of a button a pump turns on, rapidly pushing the ambient temperature water out of the hot water lines and into the cold-water lines en route back to the water heater. This ambient temperature water, which is normally lost down the drain, is replaced by hot water. When the hot water reaches a distant fixture, a thermal sensor detects the temperature rise and quickly shuts the pump off.

By using the existing cold-water line as the return line, an on-demand delivery system can be easily and cost-effectively retrofitted in existing homes. Because of the thermal sensor, the system will not allow hot water to cross over to the cold-water line, thus ensuring that all cold-water faucets still have cold water.

Energy is conserved: approximately 30 seconds after pushing the button, hot water arrives at the faucet and the pump shuts off.  Water is conserved: there is no cold water flowing down the drain while waiting for the hot water to arrive. The users are happy: 30 seconds after pushing the button, they can turn on the faucet and have nearly instantaneous hot water, while knowing that they are conserving water and energy.