Multi-Unit Residential Buildings

Transcription

1 Multi-Unit Residential Buildings Energy and Water Efficiency This document has been designed to provide a general understanding of the principles and practical considerations involved in implementing cost-effective energy and water efficiency measures in existing MURBs. The measures have been organized from the easiest to implement to the more complex. The simple payback for each measure is fairly broad, given the wide variations in factors affecting costs and savings. Users should complete their own assessment based on actual capital costs and estimated annual energy savings for an individual measure. Where appropriate, other factors specific to individual measures have been identified in their description. This document is intended as a guideline only and is not intended to replace professional advice. Prior to incorporating any energy or water efficiency measures into existing MURBs, it is recommended that they be reviewed by qualified energy management professionals. All work must be performed in accordance with applicable codes and standards. Introduction Properly maintained electrical systems will help ensure comfort, convenience and safety for residents. There are electrical retrofit opportunities that can help optimize system operation based on demand and substantially reduce energy consumption. This section of the manual includes the electrical system retrofit measures that can enhance the efficiency of your electrical system, improve safety and prolong the service life of your electrical equipment. Importance of maintenance Building operators should be familiar with electrical panels and other electrical system components. Most electrical system deficiencies can be prevented by: periodic inspections (breakers usually require monthly testing); thermographic testing of systems during high load periods to help identify electrical system hot spots; selective component replacement; tightening of main connections (this procedure should be performed by an electrician); periodic cleaning of large electrical switchgear; and regular testing of standby/emergency generators. For more information on maintaining your building equipment and systems, refer to cmhc.ca.

2 Implementing safe repairs A maintenance request form (completed by residents when they notice a problem) will help to identify electrical repairs. Collect important information about the history of the problem and determine if there are any trends. Determine whether the failures occur mostly in specific locations (for example, on one side of the building where air conditioners or heaters may be in operation). When repairs are required, remember the following guidelines: Repairs should be performed immediately. Always use quality components that are acceptable to the manufacturer. Electrical problems should be serviced by persons qualified or licensed for electrical work. In most cases this requires an outside contractor. Basic repair items include replacement of thermostats and electrical controls, and changing of fuses or breakers. Follow established Canadian Electrical Code (or the provincial equivalent) guidelines. Maintenance, repair and retrofit opportunities This section describes a number of electrical system measures that have been organized from the easiest to implement to the more complex. LESS MORE 1 Reduce electrical consumption for garage ramp heaters 2 Add thermostatic controls to block heaters 3 Install electric demand controls 2

3 1 Reduce electrical consumption for garage ramp heaters Measure Install a snow- and ice-sensing control that will operate parking garage ramp heaters only when they are required, or convert the existing electric ramp heater to a wet heat type using pipes in the ramp supplied by a boiler heating an anti-freeze solution. Application MURBs with an electric garage ramp heater for melting snow and ice. Benefits Reduces energy consumption and costs for melting snow and ice. Reduces electricity demand charges for months where heater is not required. Automatically reduces buildup of snow and ice on ramps for improved safety. Improves tenant satisfaction by removing snow and ice as required. Extends the life of the ramp heating system. Considerations This measure requires a qualified contractor. Payback Simple payback for snow sensor control: 1 to 2.5 years. Simple payback for conversion to glycol system: 8 to 10 years (less if ramp must be replaced anyway. Final payback will depend on these factors: Effectiveness and/or management of existing controls. Cost and type of new controls. Snow sensors for electric ramp heater application are readily available. Where a building has less costly fuels available, consider converting the ramp heating system to an in-slab glycol circulation system that can be heated from the main heating plant or by a separate gas- or oil-fired boiler. Conversion of electric ramp heating to a glycol loop will require taking the ramp out of service for a period of time. Ensure there are alternate parking arrangements. This retrofit provides quick payback if the garage ramp is to be re-laid due to failure of an electric ramp heating system or due to surface deterioration. A significant reduction in the operating time of the electric ramp heater may eliminate consideration of other alternatives such as conversion to a lower-cost energy source. The sensor system will have to be able to adjust to account for slush accumulation after a snowfall. Custodian education and ongoing monitoring of energy bills are essential for identifying malfunctions before they incur high costs. 3

4 Implementation Ensure that the system is equipped with a manual ON/OFF switch and an override switch to turn on the heater for a preset period of time. If a ramp heater has a history of failure and is in need of repair, consider the construction of an enclosure around the ramp and relocating the door to the top since ramp heating will not be required if the ramp is enclosed. 4

5 2 Add thermostatic and time controls to block heaters Measure Control timing of availability of power at block heater receptacles based on outdoor temperature and time of day to reduce energy usage. Payback Simple payback: 2 to 4 years. Application MURBs with block heater receptacles for automobiles. Benefits Substantially reduces energy used for block heaters. Reliable delivery of heat required for starting engines in the morning. Reduces pollutant emissions from vehicles on start-up. Considerations This measure requires a qualified tradesperson. Vehicles in need of a tune-up or with poor battery charging systems may not start in colder weather. Should complaints arise, inform the car owner about the manufacturers recommendations on starting temperatures. Tenants may complain when they discover there is no power in the receptacles, especially if they plan to use the power for some other purpose. Setting of the timer may have to be adjusted to accommodate the departure time of occupants. Implementation This measure consists of a timer and thermostat control connected to a block heater circuit. According to automobile manufacturers recommendations, use of block heaters is not required above temperatures of -9 C (16 F), and need only be activated three to four hours before the vehicle is to be started. Establish where the new equipment will be located (either inside an existing room close to the electrical panel or outside in a weatherproof cabinet on a pole). The new control devices will be added. The existing electrical wiring, overcurrent protection and receptacles will not be changed. Timer should be a 24-hour, single-point type set to provide power between 3:00 a.m. and 9:00 a.m. (or as determined by tenant requirements). Depending on the schedule of the residents, a lunchtime on setting may be required as well. An override thermostat should be connected in series with the timer to prevent heater operation above -9 C (16 F). A contactor rated at the total capacity of the circuit will be actuated by the timer and thermostat. 5

6 3 Install electric demand controls Measure Install electric demand controls on large electrical loads to prevent their operation during periods of high electrical demand. Application MURBs with large electrical loads, such as space heating, ramp heating, domestic hot water (DHW) heating, ventilation air heating and pool heating. Benefits Significantly reduces monthly demand charges on electricity bills and reduces electricity costs. Considerations Peak demand typically is the maximum electrical load (in kw) in use for at least 15 minutes in one monthly billing period. In MURBs, peak load typically occurs between 5 p.m. and 7 p.m. Preventing non-essential loads from being used at this time by automatically turning them off (also called load shedding) for a short time will reduce peak demand charges. Payback Simple payback will vary considerably. Final payback will depend on these factors: The reduction in demand that can be achieved for each of the twelve months of the year. The relationship between costs for demand and energy as defined by the rate structure. This measure requires an energy consultant who will determine the loads that are not required during peak demand periods, and acceptable shut-off periods to ensure that essential services are maintained. A qualified contractor is required for implementation. Loads that can take advantage of stored energy (for example, DHW) are ideal for this measure. Ensure that equipment can be shut down and restarted without interrupting internal controls such as timers or resets. Some MURBs are not charged for peak electrical demand. Confirm the presence of demand charges before considering demand control measures. 6

7 Implementation There are three approaches to controlling peak demand: Timer control of non-essential loads. This is the least costly, shortest payback option. Unloading of selected non-essential loads in response to measured electrical demand. Microprocessor-based controls for all loads. The most appropriate demand control system will be based on the following: The electricity demand recordings from the utility to establish time, magnitude and duration of peaks. Electric utilities will usually install a demand recorder for a nominal fee. A log of demand readings (preferably in the winter) can be taken for every 15 minutes to 1 hour over one week. 7

8 Other modules in the Multi-Unit Residential Buildings Energy and Water Efficiency series Heating and Ventilation Systems (OPIMS 68752) Lighting Systems (OPIMS 68754) Building Envelope (OPIMS 68756) Renewable Energy (OPIMS 68760) Electrical Systems (OPIMS 68762) Water Conservation (OPIMS 68764) Domestic Hot Water (OPIMS 68758) cmhc.ca 2016, Canada Mortgage and Housing Corporation Printed in Canada Produced by CMHC Although this information product reflects housing experts current knowledge, it is provided for general information purposes only. Any reliance or action taken based on the information, materials and techniques described are the responsibility of the user. Readers are advised to consult appropriate professional resources to determine what is safe and suitable in their particular case. Canada Mortgage and Housing Corporation assumes no responsibility for any consequence arising from use of the information, materials and techniques described.